How can you accurately identify a brown recluse spider. What are the key characteristics to look for when distinguishing brown recluses from other spiders. Why is proper identification important for safety and peace of mind.

Understanding the Brown Recluse: Appearance and Habitat

The brown recluse spider (Loxosceles reclusa) is a species that often sparks fear and concern due to its venomous bite. However, accurate identification is crucial to avoid unnecessary panic and misdiagnosis. Let’s explore the key features that define this arachnid:

• Size: Approximately 3/8 inch body length
• Color: Light to dark brown
• Distinctive mark: Dark brown violin shape on cephalothorax
• Eyes: Six eyes arranged in three pairs
• Legs: Uniformly colored, no bands or stripes
• Abdomen: Single color, varying from cream to dark brown
• Habitat: Prefers secluded areas, makes small retreat webs

Understanding these characteristics is essential for proper identification. However, it’s important to note that many spiders are often misidentified as brown recluses due to similar markings or coloration.

The Violin Pattern: A Misleading Identifier

While the brown recluse is known for its violin-shaped marking, this feature alone is not a reliable means of identification. Many spiders have markings that can be mistaken for a violin shape, leading to false identifications. Instead, focus on the complete set of characteristics, with special attention to the eye arrangement.

Common Misidentifications

Spiders frequently mistaken for brown recluses include:

• Cellar spiders (Psilochorus and Physocyclus genera)
• Wolf spiders
• Huntsman spiders
• Orbweavers

These species may have similar coloration or markings but differ in crucial aspects such as eye arrangement, leg banding, or body shape.

The Crucial Eye Pattern: Six Eyes in Three Pairs

The most reliable feature for identifying a brown recluse is its unique eye arrangement. Unlike most spiders that have eight eyes, brown recluses have six eyes arranged in three distinct pairs. This configuration forms a semicircle on the front of the cephalothorax.

How to Examine Spider Eyes

Examining a spider’s eyes requires careful observation and possibly magnification. Here’s a step-by-step guide:

1. Use a magnifying glass or macro lens
2. Ensure proper lighting
3. Look for three distinct pairs of eyes
4. Note the spacing between the pairs
5. Compare to reference images of brown recluse eye patterns

Remember, if you count eight eyes or see a different arrangement, you can rule out the brown recluse.

Geographic Distribution: Where Brown Recluses Are Found

Understanding the natural range of brown recluse spiders is crucial for accurate identification. These spiders are primarily found in the central and southern United States, with their range extending from Nebraska to Ohio and south to Georgia and Texas.

Range Map Interpretation

Consult a reliable range map to determine if you live in an area where brown recluses are typically found. If you’re outside this range, the likelihood of encountering a brown recluse is extremely low, though not impossible due to occasional transportation in goods.

Do brown recluses exist outside their typical range? While rare, isolated populations or individual spiders can occasionally be found in non-native areas, usually due to accidental transportation. However, these occurrences are extremely uncommon and should not be a significant concern for those living outside the spider’s natural range.

Debunking Brown Recluse Bite Myths

The fear surrounding brown recluse spiders often stems from exaggerated reports about their bites. It’s crucial to understand the reality of brown recluse envenomation to maintain a balanced perspective.

Facts About Brown Recluse Bites

• 90% of bites are not medically significant
• Many heal without medical intervention
• Severe reactions are rare
• Many reported “bites” are misdiagnosed

What causes the misdiagnosis of brown recluse bites? Several medical conditions can produce symptoms similar to a brown recluse bite, including:

• Necrotizing bacterial infections
• Pyoderma gangrenosum
• Diabetic ulcers
• Lyme disease
• Adverse reactions to medications

This underscores the importance of seeking professional medical evaluation rather than self-diagnosing based on symptoms alone.

Look-Alikes: Spiders Commonly Mistaken for Brown Recluses

Many spiders share similar characteristics with brown recluses, leading to frequent misidentifications. Understanding these look-alikes can help in accurate spider identification.

Common Brown Recluse Look-Alikes

1. Cellar Spiders (Pholcidae family):
   • Similar light brown coloration
   • May have violin-like markings
   • Distinctly different: long, thin legs and 8 eyes
2. Wolf Spiders (Lycosidae family):
   • Brown coloration
   • Robust body shape
   • Distinctly different: 8 eyes in three rows, hairy appearance
3. Huntsman Spiders (Sparassidae family):
   • Large, brown spiders
   • May have violin-like markings
   • Distinctly different: Crab-like leg arrangement, 8 eyes
4. Spitting Spiders (Scytodidae family):
   • Similar 6-eye arrangement
   • Light brown coloration
   • Distinctly different: Dome-shaped cephalothorax, lack of violin marking

How can you differentiate these look-alikes from true brown recluses? Focus on the combination of characteristics unique to brown recluses: six eyes in pairs, uniform leg color, and lack of distinct markings on the abdomen.

Brown Recluse Behavior and Habitat Preferences

Understanding the behavior and preferred habitats of brown recluse spiders can aid in identification and prevention of encounters.

Typical Brown Recluse Behavior

• Nocturnal: Most active at night
• Shy: Prefer to avoid human contact
• Non-aggressive: Rarely bite unless directly threatened
• Web-building: Create small, irregular webs for shelter

Preferred Habitats

Brown recluses are well-adapted to human environments and are often found in:

• Cluttered basements and attics
• Cardboard boxes and storage areas
• Behind furniture and picture frames
• In closets and rarely-disturbed spaces
• Woodpiles and outbuildings

What measures can be taken to reduce the likelihood of brown recluse encounters in the home? Implementing regular cleaning routines, decluttering, and sealing potential entry points can significantly reduce the chances of brown recluse infestations.

The Importance of Professional Identification

Given the complexities of spider identification and the potential consequences of misidentification, seeking professional expertise is often the best course of action.

Benefits of Expert Identification

• Accurate species determination
• Proper risk assessment
• Appropriate control measures if necessary
• Peace of mind for homeowners

Where can you find expert spider identification services? Many universities with entomology departments offer identification services, as do some pest control companies and natural history museums. However, it’s important to note that due to economic constraints, some institutions may have limited capacity for public identifications.

DIY Identification Tips

If professional identification is not immediately available, here are some steps for preliminary self-assessment:

1. Safely capture the spider if possible
2. Take clear, well-lit photographs from multiple angles
3. Note the location and circumstances of the find
4. Compare against reliable identification guides and resources
5. Consider the geographic likelihood of brown recluse presence

Remember, when in doubt, it’s always better to err on the side of caution and seek professional advice.

Prevention and Control: Managing Brown Recluse Populations

While brown recluse spiders are not aggressive, their presence can be concerning. Implementing prevention and control measures can help manage populations and reduce the risk of encounters.

Prevention Strategies

• Seal cracks and crevices in building exteriors
• Reduce clutter in basements, attics, and storage areas
• Use airtight storage containers instead of cardboard boxes
• Regularly clean and vacuum potential hiding spots
• Install door sweeps and window screens
• Keep beds away from walls and use bed skirts

Control Methods

If brown recluse spiders are confirmed in your home, consider these control options:

1. Sticky traps placed along walls and corners
2. Regular inspection and removal of webs
3. Use of diatomaceous earth in crawl spaces and voids
4. Professional pest control services for severe infestations

Is it necessary to use chemical pesticides for brown recluse control? In most cases, non-chemical methods and habitat modification are sufficient for managing brown recluse populations. Chemical treatments should be considered a last resort and applied only by licensed professionals.

Brown Recluse Myths vs. Facts: Separating Truth from Fiction

Misinformation about brown recluse spiders abounds, leading to unnecessary fear and misguided actions. Let’s dispel some common myths and establish the facts.

Common Brown Recluse Myths

1. Myth: All brown spiders are brown recluses

   Fact: Many brown spiders are harmless and unrelated to recluses

2. Myth: Brown recluses are aggressive and seek out humans to bite

   Fact: They are shy and only bite in self-defense when trapped against skin

3. Myth: Brown recluse bites always cause severe necrosis

   Fact: Most bites heal without significant complications

4. Myth: Brown recluses are common throughout the United States

   Fact: They have a limited geographic range in the central and southern U.S.

5. Myth: You can identify a brown recluse bite by a bullseye pattern

   Fact: Many conditions can cause similar wound patterns; medical diagnosis is necessary

Why do these myths persist despite scientific evidence to the contrary? Media sensationalism, internet misinformation, and the human tendency to fear the unknown all contribute to the perpetuation of these myths. Education and reliance on credible sources are key to dispelling these misconceptions.

The Role of Brown Recluses in Ecosystems

While often viewed negatively due to their venomous nature, brown recluse spiders play important roles in their native ecosystems.

Ecological Functions of Brown Recluses

• Pest control: They prey on various insects and arthropods
• Food source: They serve as prey for birds, lizards, and other spiders
• Biodiversity: They contribute to the diversity of arachnid species
• Indicator species: Their presence can indicate specific environmental conditions

How does the presence of brown recluses impact local ecosystems? In their native habitats, brown recluses help maintain insect populations and contribute to the complex food web. Their role underscores the importance of preserving biodiversity and maintaining ecological balance.

Conservation Considerations

While not endangered, brown recluses face challenges from habitat loss and pesticide use. Conserving these spiders involves:

• Preserving natural habitats
• Promoting integrated pest management
• Educating the public about their ecological importance
• Encouraging research into their biology and behavior

By understanding and appreciating the role of brown recluses in nature, we can develop more balanced approaches to managing their presence in human-inhabited areas.

Future Research and Understanding of Brown Recluse Spiders

As our knowledge of brown recluse spiders continues to evolve, ongoing research is crucial for improving identification, management, and medical treatment related to these arachnids.

Current Areas of Brown Recluse Research

• Venom composition and potential medical applications
• Improved diagnostic techniques for brown recluse bites
• Population dynamics and range expansion studies
• Development of more effective and eco-friendly control methods
• Genetic studies to understand population variations

What potential benefits could arise from advanced brown recluse research? Improved understanding of brown recluse venom could lead to new medical treatments, while better population studies could inform more effective and targeted management strategies.

Citizen Science and Public Involvement

The public can contribute to brown recluse research through:

1. Participating in spider identification apps and platforms
2. Reporting sightings to local university entomology departments
3. Supporting habitat conservation efforts
4. Engaging in community education programs about arachnids

By fostering a greater understanding and appreciation of brown recluse spiders, we can move towards more informed and balanced approaches to living alongside these fascinating arachnids.

How to Identify and Misidentify a Brown Recluse Spider

How to Identify and Misidentify a Brown Recluse Spider

by Rick Vetter Staff Research Associate, UC Riverside Dept. of Entomology

Updated Jan 2005

Because of media hyperbole and anxiety-filled stories by the general public extolling the horrors associated with brown recluse spiders, people are very interested in knowing if the spiders they find are brown recluses.   Although it is true that a brown recluse has a violin pattern, many non-arachnologists creatively misinterpret many markings on spiders as “violins” and feel that they have found recluse spiders.  Therefore, if you can learn to identify your spider as NOT a recluse, you can relieve your worries.  You won’t be able to tell what it is (and please don’t send them to me for identification because due to shift in the California economy, I no longer provide these services) but you will at least know that it is not a recluse spider.

Several important things:

1. Check the map to see if you live in an area that is supposed to have recluse spiders.   If you do not live in any of the colored areas in the map, then it is HIGHLY UNLIKELY that you have a recluse spider.  It is POSSIBLE but incredibly unlikely.
2. Because so many people have mistaken markings on a spider as violins, this is NOT a reliable characteristic for a non-arachnologist.  You need to look at the eye pattern.
3. Even if you have a recluse, bites from them are extremely rare, despite all the stories.    Many of the really graphic nasty wounds you see on the internet as recluse bites can also be other conditions like necrotizing bacteria and pyoderma gangrenosum.  Ninety percent of brown recluse bites are not medically significant, heal very nicely often without medical. intervention and treatment for most brown recluse bites is simple first aid (RICE therapy – Rest, Ice, Compression, Elevation).  Many conditions are misdiagnosed as recluse bites when their cause is something else like infection, bad reaction to medication, diabetic ulcers, Lyme disease, or other underlying medical conditions.

What does a brown recluse look like?

A brown recluse has a dark brown violin shape on the cephalothorax (the portion of the body to which the legs attach).  The neck of the violin points backward toward the abdomen.  However, what you should look at instead is the eye pattern of 6 eyes in pairs with a space separating the pairs.  Most spiders have 8 eyes in two rows of four.

Here are the things that describe a brown recluse spider (but some other spiders have a few of these characters too).  There are pictures below to illustrate what is NOT a recluse.

• Six eyes arranged in pairs, with one pair in front and a pair on either side.
• A dark violin shape on the cephalothorax.
• Uniformly light-colored legs – no stripes, no bands
• Uniformly colored abdomen which can vary from cream to dark brown depending on what it has eaten, however, it will never have two colors of pigment at the same time.   (The little discoloration on the spider above left is the heart which can be seen through the thin skin.)
• No spines on the legs, only fine hairs
• Recluses make small retreat webs behind objects, never out in the open.
• It is about 3/8 of an inch in body length.

All of the specimens shown below have been submitted to me as brown recluses!!!!!!  None of the spiders below should be considered dangerous.

Six eyes, not eight

You may not always be able to count the eyes and some eye pairs are so close together that you might not be able to see both of them, however, the 6 eye pattern of the brown recluse is easy to see with minor magnification.  Most spiders can be eliminated as NOT brown recluses simply from this aspect.  Be aware that there are spitting spiders (genus Scytodes) (below) which have a similar eye pattern but they do NOT have a violin (plus it has more than one color on its legs and abdomen).

Dark violin pattern

People have submitted the following spiders because they thought that they saw violins on their bodies.   People also claim to see the violins on the top and bottom of the abdomen, and the underside of the cephalothorax. In the left photo, the two light spiders look like they have violins but they also have 8 eyes (although you need a microscope to see all 8 of them) and more than one pigment on the abdomen so they are not recluses (they are cellar spiders, genus Psilochorus and/or Physocyclus).  The other spider in the left picture has a very faint dark line pattern which people assume is a violin.  It also has 8 eyes and massive spines on its legs, so it is not a recluse.  In the right photo, this spider has a slight darkening near its eyes so people mistake this for a recluse violin.  This spider has 8 eyes clumped together and black spines on its legs although you may not be able to see the spines in this image (genus Kukulcania).

Uniformly colored legs and uniformly colored abdomen

If there is more than one color on the legs, or if the legs are brown or darker, it is NOT a recluse.   If the spider has more than one pigment on the abdomen, it is NOT a recluse.  The top two spiders are funnel weavers (family Agelenidae), the bottom left is an orbweaver (family Araneidae), and the bottom right spider is a male huntsman spider (Heteropoda venatoria) found most often in Florida but occasionally in other gulf coast states.  They are can be determined to be NOT recluses by more than one color on their legs or abdomens.

Fine hairs only, no spines

If the spider has conspicuous thick spines on the legs, it is NOT a recluse. This orb weaver below has many spines sticking out perpendicularly from the legs.

Web made out of sight

If the spider has a conspicuous web out where you can see it, or between two trees or in rose bushes, it is NOT a recluse.  The “classic” spider webs like that of Charlotte’s Web are made by orb weavers.

Not larger than 1/2 inch in body length

If the spider has a body length of greater than half an inch, it is NOT a recluse.

Brown Recluse Spider

It can be said that no other “bug” generates as much fear as the spider. Fear of spiders ranks as one of our greatest phobias, along with fears of snakes, heights and public speaking.

Of course, most of the negative publicity spiders receive is undeserved. It’s been suggested that because some spider bites may have resulted in negative consequences for our prehistoric ancestors, that fearing spiders is adaptive, as it helps us avoid debilitating consequences. Yet there are a couple of problems with this theory.

First, “arachnophobia” affects only a few of us – why not all of us? If spider bites can seriously harm or kill us, why don’t we all have an innate fear of spiders? This leads to another problem with attempts to justify the fear of spiders: On the whole, spiders just aren’t that dangerous. While virtually all spiders use their fangs to inject venom, the fangs of many of the more than 3,500 spider species in the United States are incapable of penetrating human skin. Fewer still are the number of species capable of producing bites with complications more severe than the average mosquito bite or bee sting. And spiders are rarely aggressive toward humans; they bite only in self defense.

Others claim that fear of spiders comes to us because spiders are simply “creepy.” It’s true that many spiders creep along on their eight legs in search of prey that consists of insects and other arthropods including spiders. Many species lie in ambush, hidden in cracks, crevices and holes, or camouflaged on vegetation, waiting to strike at insects that venture too close. Other species wait for prey to become entangled in webs they construct of silk produced from spinnerets located on the end of the abdomen.

Spider silk is the strongest fiber in nature, five times stronger than steel, yet 30 times thinner than human hair. Different spiders use silk in different ways: for webs or retreats, to subdue and wrap prey, to line their nests and nurseries, and to form egg sacs. Silk also is used for movement. Some spiders use “drag lines,” for example, to drop down from a ceiling or a leaf. Many spiders, especially young ones, or “spiderlings,” are capable of “ballooning.” A ballooning spider extends a long line of silk that enables it to be carried aloft on winds that can transport the spider to places many miles away.

“Spinnerets, fangs and eight legs” would be a good answer to the question, “What is a spider?” For another special characteristic, we can simply look into the spider’s eyes. Most spiders have eight of them. The size and arrangement of a spider’s eyes are keys to its identity.

Another unique anatomical feature are a spider’s pedipalps. There are two of these appendages positioned just outside the fangs. They are sensory devices, perhaps like our tongue or the antennae of insects. But a male spider uses its pedipalps, which look a little like miniature boxing gloves, in courtship “dances” and to insert sperm into the female’s body during copulation.

Finally, spiders are not “bugs” nor are they insects. But like insects they are arthropods related to crabs, lobsters, shrimp and others. Specifically they are arachnids, whose close relatives include mites, ticks and scorpions. Unlike insects, spiders have a two-part body, a cephalothorax and abdomen.

Spiders Found Outdoors

It’s estimated that wherever we go we are never more than a few feet away from a spider. There are more than 500 different kinds of spiders in Illinois, living in a variety of habitats. Yet only a few species are frequently found indoors. A few others are peri-domestic — encountered on and around the exteriors of structures, into which they occasionally wander.

CRAB SPIDERS (Thomisidae)

Instead of waiting in webs, these spiders ambush insects that land on the flowers and vegetation around them. Some are brightly colored to match the flowers they rest on. Other species, such as the running crab spiders (Philodromidae), search more actively for prey and are occasionally found on walls and ceilings after wandering indoors.

Crab spiders are named for their crab-like movement and the arrangement of their legs, the first two pairs being much longer than the others. Most are small spiders with bodies about ¼-inch long. Crab spiders that find their way indoors usually get there by hitchhiking on flowers and plants brought in from outside. Bites are very rare and inconsequential.

ORB WEAVER SPIDERS (Araneidae)

For many of us it is an orb weaver spider that comes to mind when we think of spiders. The orb weavers are usually large, colorful spiders that spin the classic spider web with silken spokes held together by concentric rings of silk.

These are the spiders of imagination, Halloween and haunted houses. Yet they are almost always found outdoors.

The large webs of many orb weavers are often found in tall vegetation or attached to porches, barns and other structures. The spider sits in the middle of its web or hides nearby, waiting for the web to vibrate, signaling the entanglement of an insect which it will quickly wrap in silk. Large egg sacs are produced in the fall.

This group includes the garden spiders (Argiope spp.), strikingly colored black with yellow or orange markings, their bodies can be an inch long. Their webs may span two feet or more in diameter. Also included are the spiny-backed spiders (Micrathena spp., Gasteracantha spp.) found in the forest and garden. They have spike-like projections on their abdomens and are often brightly colored. Bites from orb weaver spiders are uncommon and similar to a bee sting.

JUMPING SPIDERS (Salticidae)

If any spider can be considered “cute” it would be a jumping spider. While some people consider these “mini tarantulas” as pets, others find their jumping a bit disconcerting. Although bites may produce a sharp pain, they are not considered dangerous.

Many jumping spiders (e.g., Phidippus spp.) are black, appear fuzzy and are marked with red, white or iridescent green. Two of the jumping spider’s eyes are much larger than the other six. They seem to have good vision and sometimes turn to face those that disturb them. Able to see prey several inches away, they hunt by day, pouncing on insects, spiders, etc., and hide at night in silken retreats in cracks and crevices.

Jumping spiders have stout bodies usually less than ½-inch long. Smaller species such as the zebra spider (Salticus scenicus) are striped black and white and often found at windows.

WOODLOUSE SPIDER (

Dysdera crocata)

This spider is sometimes mistaken for the brown recluse spider, though there is only a vague resemblance between the two. Yet, like the brown recluse, the woodlouse spider has six eyes and is most active at night.

This spider has a ½-inch long body. Its legs are reddish, its front half a dark reddish brown, and its abdomen gray. It has long, sickle-like jaws for feeding on woodlice (also known as pillbugs or sowbugs) which it hunts under rocks and logs. While this spider may become defensive when threatened, bites usually result only in redness around the bite and pain that lasts for less than an hour.

NURSERY WEB SPIDERS (Pisauridae)

These spiders are among those that occasionally wander indoors largely by accident. Nursery web spiders are large, formidable spiders resembling wolf spiders. Their bodies are up to an inch long and their legs may span more than 3 inches.

The most striking of nursery web spiders are the fishing spiders (Dolomedes spp.). Most live along the water’s edge and are frequently seen around docks and on shoreline and aquatic vegetation. There they hunt for prey that consists mostly of terrestrial and aquatic insects, but also can include small fish, tadpoles and frogs.

Fishing spiders can run over the surface of the water by utilizing special hairs on their feet. They also can dive into the water to pursue prey, or when disturbed, carry with them a bubble of air that allows them to stay submerged for a half-hour or more.

Nursery web spiders get their name from using silk to bind leaves together, forming a shelter for their young. A female will carry the egg sac in her mouth, place it inside the “nursery” and guard the eggs and spiderlings after they hatch.

Bites from nursery web spiders may be painful but are not considered dangerous.

WOLF SPIDERS (Lycosidae)

Any large, hairy spider in the eastern half of the United States is more than likely a wolf spider. These spiders may grow to have bodies 1 inch long with a leg span of 2 or more inches. They are generally black or gray in color, but sometimes reddish, brown or tan. Two of their eight eyes are often larger than the rest.

Wolf spiders are active hunters that search for prey day or night. Some burrow and others rest in silken retreats beneath rocks, logs and vegetation. Females attach their egg sacs to their spinnerets and carry the egg sacs and spiderlings around after they hatch.

As with other large spiders, the bite of a wolf spider is likely to be felt but is not considered dangerous. Bites from these and other large spiders are not common.  

FUNNEL WEB SPIDERS (Agelenidae)

Though they may occasionally wander into structures, funnel web spiders are typically found around the foundation of homes and in grasses and bushes. They remain hidden deep inside funnel-shaped webs that are quite noticeable on dewy mornings. Unlike many other web-building spiders, funnel web spiders are fast runners. When an insect or another spider happens by, the funnel web spider rushes out to subdue its prey.

The group includes medium-sized species such as the grass spiders (Agelenopsis spp.), usually found outdoors, and house spiders (Tegenaria spp.) which often occur indoors. Grass spiders are often brown with dark stripes on their backs.

Their spinnerets are easily seen trailing from the tips of their long abdomens. The house spiders are brown with chevron-like markings on their abdomens.

None of the funnel web spiders inhabiting the United States should be considered dangerous. The bite of one species, the hobo spider (Tegenaria agrestis) has been implicated as a source of necrotic wounds. However, this has not been well-documented and it should be noted that the hobo spider is not considered dangerous in its native Europe. In the United States, the hobo spider inhabits only the Pacific Northwest from Utah to Washington. A very similar species, the common house spider (Tegenaria domestica) occurs throughout the United States and is easily mistaken for the hobo spider.

Spiders Found Indoors

Some types of spiders are commonly found living and reproducing indoors. Included here are spiders that most of us have had frequent encounters with (cellar spiders and cobweb spiders), as well as some of medical importance (widow spiders and brown recluse spiders).

CELLAR SPIDERS (Pholcidae)

These spiders are sometimes called “daddy-longlegs” because of their long, delicate legs. Their tiny bodies are not more than ¼-inch long. Cellar spiders are most often seen hanging upside down in sheet-like or irregularly-shaped webs in corners near the ceiling or floor. The webs can quickly accumulate and become unsightly nuisances in cellars, basements or commercial buildings such as warehouses.

COBWEB SPIDERS (Theridiidae)

The bulbous abdomen and much smaller head section of the cobweb spider gives it a characteristic spider shape. The group includes many medium-size species with bodies about ½-inch long that are black to brown in color with various patterns and markings.

Cobweb spiders are also known as comb-footed spiders because of the comb-like bristles on the last segments of their hind legs which are used to wrap prey. These spiders hang in irregularly shaped webs that are usually positioned close to the floor in moist crawlspaces, basements and garages. If one web is unproductive, the spider will build another nearby, leaving the old web to gather dust and become a “cobweb.”

Widow spiders, such as the black widow (Latrodectus mactans), are cobweb spiders with bites that can be dangerous. But while the cobweb spiders typically found in homes may resemble widow spiders, their bites are not dangerous. Cick here for more information on black widow spiders.

SAC SPIDERS (Miturgidae and Clubionidae)

These are small to medium-sized spiders that make “sacs” – tubular webs about 1-inch long, typically positioned between angled surfaces. The sacs are used as “retreats,” that is, the spiders rest in them by day and emerge at night to wander in search of prey. The retreats may be abandoned after only one day’s use, so household infestations of sac spiders are often easily identified, even without seeing the spiders, due to the prevalence of sacs around door and window frames, in corners, and where walls and ceilings meet.

Yellow sac spiders (Chiracanthium inclusum and C. mildei) are the most common species indoors. Their bodies are about ¼-inch long and, including legs, the spiders are less than the size of a quarter. They are a pale yellow color.

Yellow sac spiders are fast-running, nocturnal hunters that can be found from floor to ceiling in structures and will drop on a line of silk when disturbed. They also are common outdoors where they live in vegetation and often enter homes as temperatures drop in fall.

Because they are common indoors and may bite instinctively when touched, yellow sac spider bites may be more common than bites from any other spider in the United States. At least some of the injuries listed by medical personnel and poison control centers as “spider bites” or “brown recluse bites” are those of the yellow sac spider. Reactions to sac spider bites may vary. The bite is often felt as a sharp pain. Localized redness and swelling typically develop and dissipate within two hours.

BROWN SPIDERS (Sicariidae)

There are several species of brown spiders in the United States. Most occur in the desert southwest. But the brown recluse (Loxosceles reclusa) inhabits the southeastern quarter of the United States, as far north as southern Illinois. Discoveries of brown recluse outside this range are rare.

The brown recluse is a small-bodied, medium-sized spider whose outstretched legs span little more than the diameter of a quarter. It is almost uniformly brown and without banded legs or other prominent markings – except for the dark violin-shaped mark on its cephalothorax, just behind its eyes. Unlike most spiders, the brown recluse has six eyes arranged in three pairs, instead of the usual eight.

Brown recluse are hunting spiders that wander at night in search of prey. Females make retreats in which they hide and ambush prey. A retreat consists of a mat of silk spun in a hidden location such as in a wall void or behind a picture frame. The brown recluse seems to prefer to rest on wood and paper surfaces.

Because brown recluse spend much of the day hiding inside furniture, boxes and stored goods, they are easily transported with these items. This and other characteristics allow them to establish themselves in new locations. They are long lived, can survive for many months without feeding, and females need mate only once to produce offspring throughout their lives. So it takes only one, mated female to start an infestation. Once established, they are difficult to control.

Yet even in heavily infested structures, brown recluse are indeed reclusive, not aggressive, and bites rarely occur. Nevertheless, physicians often misdiagnose many unrelated injuries as “brown recluse bites.” When they do occur, bites are rarely as serious as they have been portrayed. Some bites produce only localized redness and swelling. Severe necrosis probably occurs in less than 10 percent of cases, and may result more from bacterial infection of the wound rather than reaction to the spider’s venom. Click here for more information on brown recluse spiders.

MANAGING SPIDERS

As for most pests, effective spider control begins with identification. With spiders, identifying the species may not be necessary, but it is important to know whether the spider is a hunting spider or web-hanging spider.

Spiders that catch their prey in webs are usually found in or near their webs. These include cellar, cobweb, orb weaver and funnel web spiders. Often these spiders are more easily controlled than spiders that roam in search of prey. Control can be as simple as destroying the webs and squashing the spider with a fly swatter, newspaper or shoe. A vacuum cleaner works well too and leaves less mess. Vacuuming spiders and their webs is a good, non-toxic method that also can be used on hunting spiders, if you are quick enough.

A structure’s exterior is a good place to start to prevent spiders from entering.

Funnel web and sac spiders, for example, are prone to enter structures in the fall. To help prevent this, check the foundation for cracks and holes. Also check vents, around window and door frames, and for gaps around utility and cable lines. Seal these potential entry points with caulk, expandable foam, concrete or similar materials.

Try to keep doors and windows screened and shut. Install door sweeps to keep spiders from entering beneath doors. Minimize lighting that is visible from outside because lights attract insects, and insects attract spiders. If you must have outdoor lighting, use yellow “bug lights” or sodium vapor lights instead of white lights and mercury vapor lights.

Vegetation and mulch around the structure’s foundation should be kept to a minimum where possible. Maintaining a rock or gravel border about 2-feet wide around the foundation is best because vegetation and mulch attract insects and give spiders a place to build webs. Moisture accumulating around foundations and in basements and crawlspaces creates a favorable environment for insects and spiders. Moisture control measures include, sealing cracks, fixing water leaks, correcting grades, and ventilation and polyethylene sheeting in crawlspaces.

Still, some spiders may enter structures even though extensive work has been done to exclude them. Crab spiders and sac spiders may “hitchhike” indoors on flowers and plants. And brown recluse spiders enter structures, hidden in furniture, boxes and other goods. These items should be thoroughly inspected and cleared of spiders before they are brought in.

Sticky traps are another non-toxic means of insect and spider control. These traps are nothing more than adhesive on cardboard. Most sticky traps, also known as monitors, are about the size of a small letter envelope. Some can be folded into a box or triangular configuration that helps protect the adhesive from dust and debris.

Sticky traps can be purchased at lawn-and-garden centers, discount and hardware stores, from pest control product retailers and distributors, and on the Internet. They can be effective against hunting spiders including funnel web, wolf, nursery web, woodlouse and brown recluse spiders. Traps should be placed indoors wherever these spiders travel, e.g., along walls, behind furniture, and around potential entry points such as garage doors. For species that typically run across flooring, such as brown recluse spiders, the use of sticky traps – and lots of them – is important, not only to trap the spiders, but to help pinpoint infested parts of the structure that can be sealed and/or treated with pesticides if necessary.

Pesticides can be effective against spiders, but in many cases control is not achieved by the use of pesticides alone. As with many pests, the greatest degree of control results from the combined use of several control methods, that is, integrated pest management.

The application of pesticides around a structure’s foundation, known as a barrier or perimeter treatment, can be effective, for example, when applied in early fall to help prevent sac spiders from entering. However, perimeter application may not be necessary if vegetation, mulch, leaf litter, etc., are kept away from the foundation as mentioned above.

Indoor pesticide use is best applied to cracks, crevices and voids that harbor spiders. Dust formulations can be used in wall voids, voids around fireplaces, and in crawlspaces and attics, but should not be applied to easily accessible areas or false ceilings. Microencapsulates or wettable powder formulations can be effectively applied to attics, crawlspaces and basements as well as the structure’s exterior.

Again, proper identification of the spiders and their habits will determine which control methods are best to use and, in the end, how effective those methods will be. For some, hiring a pest management professional may be best.

Photos and illustrations courtesy of University of Nebraska, United States Fish and Wildlife Service, Peter J. DeVries – Spiders of Wisconsin: http://spiders.entomology.wisc.edu/, Richard Bradley, and Stephanie Newhouse.

NOTE: When pesticides are used, it is the applicator’s legal responsibility to read and follow directions on the product label. Not following label directions, even if they conflict with information provided herein, is a violation of federal law.

For more information, contact the Illinois Department of Public Health, Division of Environmental Health, 525 W. Jefferson St., Springfield, IL 62761, 217-782-5830, TTY (hearing impaired use only) 800-547-0466.

top 6 most poisonous spiders on the planet The drug was created on the basis of a substance from the venom of the Fraser Island funnel spider. It is known that after an attack, blood flow to the heart decreases, the oxygen content in the heart muscle steadily decreases.

The cellular environment becomes acidic, and at the molecular level, the body sends a death signal to the heart cells. Extracted from spider venom, the Hi1a protein blocks acid-sensitive ion channels, preventing the death signal from passing through them. Spider venom will thus save the lives of many people. However, the statistics can be quite the opposite. The bite of some species of arthropods is deadly to humans, and so far only Peter Parker has been lucky enough to escape with the transformation into Spiderman. But which spiders are the most poisonous?

Northern leukocobweb spider

Photo: © decem.info

Northern leukocobweb spider was previously found only in Sydney, but today it has spread throughout Australia. If you are going to visit this country, be careful. Representatives of this species have chosen burrows, tree trunks, flower pots and even doorways. Often they find themselves in pools, and swimmers who do not notice the danger in time turn out to be their victims. Under water, the northern leucoweb spider can survive up to 24 hours. His bite is hard to miss because of the pain. The main symptoms are numbness of the limbs, tongue and lips, shortness of breath. The victim is also at risk of falling into a coma. A fatal outcome is very likely, and especially these eight-centimeter arthropods are dangerous for children. Death can occur 15 to 20 minutes after contact if an antidote is not given.

Redback spider, or Australian widow

Photo: © animalreader.ru

Dangerous species Latrodectus hasselti distributed mainly in Australia and is distinguished by a black body with a red stripe on the back. Another feature is the extremely strong web. The Australian widow grows to only one centimeter, but her nerve venom can cause asphyxiation and death. Previously, there were noticeably more deaths, but an effective antidote helped change the situation. It is worth noting that only female redback spiders pose a threat to humans. A careless person is guaranteed acute pain with a number of side effects: muscle spasms, nausea and pain in the abdomen. Ice or a cold compress should be applied to the bite site.

Six-eyed sand spider

Photo: © wikipedia.org

No effective cure has been found for the venom of the six-eyed sand spider. Representatives of this species prefer to disguise themselves in the sand, and can freeze for a long time. Fine bristles throughout the body contribute to the retention of sand particles. Spiders hunt insects and even scorpions, capturing the victim with strong paws and injecting the toxin into her body. The poison causes rupture and necrosis of tissues, rupture of red blood cells and the vessels themselves. History has few cases of a sand spider attacking a person, but it is recommended that everyone avoid meeting this species. Fortunately for us, the six-eyed sand spider lives only in the desert places of Africa and South America. Often adjacent to ant colonies. Another feature is its lifespan. These spiders can live up to four times as long as their other brethren.

Chilean Recluse

Photo: © decem. info

The Chilean Recluse measures four centimeters in size, but is not striking in appearance. The impression is formed due to the inconspicuous brown color and thin constitution of the arthropod. At the same time, the hermit spider is famous for its poisonousness. Its bite causes extremely painful sensations and a strong burning sensation, comparable to a cigarette burn. After some time, cell necrosis and skin death occur. About 10 out of 100 people bitten by the “Chilean” die. Some of the survivors need long-term rehabilitation after tissue necrosis. Despite the name, the Chilean spider is also found in some European countries. For living and weaving a web, this species prefers abandoned, secluded places, which is why it is called a hermit.

Black widow

Photo: © wikipedia.org

Black widow is not only the most famous spider species, but also very dangerous. Many myths and legends are associated with the name of this arthropod, some of which are not confirmed by anything. For example, many believe that a widow bite is one hundred percent fatal. But this is not so, although spider venom is indeed stronger than rattlesnake venom. The bite of a female is deadly, so do not be afraid if a male gets angry at you. It is the females that have a characteristic appearance – a black body with a red pattern resembling an hourglass. The size of a black widow rarely exceeds two centimeters, but the poisonous glands are very impressive and filled with a very toxic substance. The genus of black widows includes more than 30 varieties living on all continents. The exception is made by especially cold regions of the Earth.

Brazilian wandering spider

Photo: © wikipedia.org

The Brazilian wandering spider is considered the most poisonous spider in the world. It is also called the “Brazilian Wandering Spider” or simply “Banana Spider”, as members of this species most often live on banana palms. Its poison is listed in the Guinness Book of Records as the most toxic and dangerous among spiders. The composition of the substance injected into the body of the victim contains the PhTx3 neurotoxin, which is used in medicine. Insects and rodents die almost instantly, the death of a larger organism can occur in 10-15 minutes. The victim experiences extremely painful sensations, in most cases dying from suffocation. In some cases, suffocation is accompanied by muscle atrophy and failure of some organs, including the heart. Brazilian wandering spiders grow up to 15 centimeters, successfully camouflage, are distinguished by aggression and assertiveness during the attack.

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