Click for a hub of Extension resources related to the current COVID-19 situation.
COVID-19 Resources

Brown recluse spider

Article author: Mike Merchant
Most recently reviewed by: Pat Porter (2018)

Common Name(s): Brown recluse spider

Description

The color of the brown recluse spider varies from light brown to greyish spider, with slender legs extending over an area about the size of a quarter to a half-dollar. Two characteristics that help distinguish this spider from similar species include the dark violin-shaped marking on the back of the front portion of the body. The three pairs of eyes are arranged in a semicircle.

“Violin” shaped marking on the head and cephalothorax. Photo Credit: Bart Drees, AgriLife Extension.

Adult brown recluse spiders are most frequently seen during the spring months. Mating season in Oklahoma, Arkansas, and Texas, lasts from April to early July, during which time female spiders produce up to five egg sacs, containing about 50 eggs each. The length of time required for development to the adult stage is slightly less than a year, and in the laboratory, spiders have been observed to live for up to two and a half years.

Origin and Distribution

The best-known of the recluse spiders inhabits many of the Southern and Midwestern states.They are often found in garages, firewood piles, cluttered cellars, and piles of stored boards. Around homes they are often found around bathrooms, bedrooms and closets, under furniture, behind baseboards and door facings, or in corners and crevices. They are most active during the night when they hunt. People are often bitten while they are asleep after rolling over one in bed. Others are bitten while putting on clothes that have been hung undisturbed near where they are hiding.

Recluse spiders, as their name implies, are generally shy. They spin nondescript white or grayish webs, where they may hide during the day. They are predators of insects and other arthropods.

Habitat & Hosts

Brown recluse spiders are insect predators. When large numbers of spiders are present in a building it usually means that insect prey are also abundant. Common prey for spiders may include crickets, silverfish, cockroaches, etc.

Look in debris, under objects, piles of wood, utility boxes, storage areas, dark areas, clothing, boxes, furniture, clutter and stacks of things. Indoors,they are mostly found in undisturbed storage areas, such as closets, crawl spaces, basements and attics, especially those that are cluttered. These spiders hunt at night and hide during the day. They prefer to be in locations that are not occupied by human traffic. They usually run for cover when disturbed.

Life Cycle

Egg, spiderling (nymph) and adult.  Brown recluse spiders lay 1-2 egg masses per year in dark, sheltered areas. The egg cases are round, about 5/8 inch (1.6 cm) in diameter, flat on the bottom and convex on top. After 24 to 36 days the spider lings emerge from the egg case. Their slow development is influenced by their nutrition and environmental conditions.

Management

If you live in the State of Texas, contact your local county agent or entomologist for management information. If you live outside of Texas, contact your local extension for management options.

Making sure doors are well sealed and outdoor lighting is shielded to avoid attracting outdoor insects like crickets. Good sanitation, regular pest control, and vacuuming dead insects will also help reduce insect food for spiders.

Unnecessary clutter in the structure should be eliminated, spider webs should be removed from interior and exterior areas, and a thorough vacuuming should be undertaken around, under, and behind furniture. Brown recluse spiders are frequently found in and around boxes stored in closets and attics. Stored boxes should be tightly taped shut to eliminate the availability as a nesting site. Clutter removal is best done before your pest control professional arrives.

Sticky cards readily trap brown recluse spiders, and do provide some spider control. Placing sticky cards in out of the way locations, especially next to walls, in closets and under furniture, can not only remove some of the spider population, but will allow you and your pest control provider to track the effectiveness of your control efforts over time.

Extensive infestations often require the services of a pest management professional.

Related Publications

https://citybugs.tamu.edu/factsheets/biting-stinging/others/ent-3003/

Bugwood Images

Black Widow Spider

Article author: Mike Merchant
Most recently reviewed by: Pat Porter (2018)

Common Name(s): Black Widow Spider

Description

Shiny, black spider with globular abdomen, usually with two reddish, triangular shaped markings on the underside of the abdomen. These markings often are joined to form an hourglass shape. The red markings vary among individuals and may look merely like spots, or a row of red spots may occur on the top of the abdomen. Immature spiders have white, yellow, orange or red markings on the top of the abdomen. The egg sac is free (not attached to flat surfaces). It is tan with a tough papery texture and is spherical with a nipple on the tip.

Origin and Distribution

Four structure-infesting species of widow spiders are found in all 48 states in the continental U.S.

Habitat & Hosts

They are not common indoors, but they are found in undisturbed sites such as basements and storage areas and prefer cluttered areas. Webs are built between stationary objects and walls. Outdoors, they prefer protected places near the ground, such as under stones, pieces of wood or brick piles or in rodent burrows and hollow tree stumps. Their favorite places are barns, sheds, meter boxes, brick veneer, barrels and woodpiles.

Widows tend to be clumsy out of their web and bites usually only occur if a hand is stuck in the web, or if a spider is inadvertently grabbed while cleaning areas like a garage or shed. Black widows come out at night and hunt in their cobweb-like webs. Since black widows don’t move easily, they wait for prey to come to them.

Life Cycle

Egg, spiderling (nymph) and adult. Lay eggs in a loosely woven cup of silk

Management

If you live in the State of Texas, contact your local county agent or entomologist for management information. If you live outside of Texas, contact your local extension for management options.

Using a flashlight, inspect corners, along edges, by light fixtures and windows as well as under cabinets and furniture. If moving any objects for inspections, wear gloves to avoid any bites. Outside inspect along the foundation of the structure, especially near areas with landscaping. Check electrical boxes, irrigation boxes and other protected areas. Use glueboards/ sticky traps in suspected areas of infestation to monitor spider populations.

Interior or exterior insecticidal sprays are generally ineffective at reducing spider populations, but may provide some repellency.

Insecticidal dusts can be used in low traffic areas such as boiler rooms, crawl spaces, and voids for long residual control of spiders.

Related Publications

https://citybugs.tamu.edu/factsheets/biting-stinging/others/ent-3003/

https://citybugs.tamu.edu/factsheets/biting-stinging/others/

Bugwood Images

Bed bugs

Article author: Mike Merchant, Robert Puckett
Most recently reviewed by: Pat Porter & Katelyn Kesheimer (2018)

Common Name(s): bed bug, bedbug

Description

Bed bugs are small, brownish, flattened insects that feed solely on the blood of animals. The common bed bug, Cimex lectularius, is the species most adapted to living with humans. It has done so since ancient times.

Adult bed bugs are about 1/4 inch long and reddish brown, with oval, flattened bodies. They are sometimes mistaken for ticks or cockroaches. The immatures (nymphs) resemble the adults, but are smaller and lighter in color. The youngest nymphs are approximately pinhead size and visible to the naked eye. Bed bugs do not have wings and do not fly, but can move quickly over floors, walls, ceilings and other surfaces.

BEd bug on dime

Bed bug on dime, taken by Pat Porter

Origin and Distribution

Bed bugs prefer to hide close to where they feed. However if necessary, they will crawl quite a ways to obtain a blood meal. Initial infestations tend to be around beds, but the bugs eventually may become scattered throughout a room, occupying any crevice or protected location. They also can spread to adjacent rooms or apartments. This can be especially problematic on college campuses, hotels and anywhere multi-housing scenarios occur. For this reason, control must be comprehensive and pest management professionals must think 3-dimensionally.

Habitat & Hosts

Bed bugs feed mostly at night, by piercing the skin of people as they sleep. However, if they are very hungry and if the light is dim, they will feed during the day. When bed bugs are not feeding, they spend their time in large, dense aggregations that consist of all life stages from eggs to adult. They use chemical communication to locate each other in these groups that are typically in flat, dark spaces.

When bed bugs bite, they inject a fluid into the skin that assists them in obtaining blood. Often, but not always, the fluid causes the skin to become irritated, inflamed and to itch. Elongated, spindle shaped welts can develop as a result of the bite. If the bites are on the limbs (arms or legs), these welts will be aligned with the long axis of the limb. This elongated, spindle shape can distinguish the welts from those resulting from mosquito or flea bites. In some cases, it may take several days for the reaction to occur.

If its feeding is undisturbed, a full grown bed bug becomes engorged with blood in 3 to 15 minutes. It then crawls back to its hiding place, where it remains for several days digesting its meal. When hunger returns, the bug emerges from hiding and seeks another meal of blood.

Life Cycle

The three life stages are egg, nymph and adult. Under favorable conditions of temperature (above 70° F) and regular feeding, female bed bugs will lay about 200 eggs during their lifetime at the rate of 3 or 4 per day. Eggs are coated with a sticky substance, causing them to adhere to objects on which they are deposited. The eggs hatch in 6 to 17 days and the nymphs begin to feed on blood immediately.

After 5 molts, bed bugs reach maturity. However, bed bugs must obtain a blood meal before each molt and females must also feed before laying eggs. There may be 3 or more generations a year. Environmental factors and the availability of food will cause considerable variation in the developmental rate of all stages of growth. Young and old bed bugs may live for several weeks to several months without feeding, depending upon the temperature.

Management

If you live in the State of Texas, contact your local county agent or entomologist for management information. If you live outside of Texas, contact your local extension for management options.

To control bed bugs in homes, locate their hiding places such as described above and treat with an insecticide approved for this use. Select a product whose label includes specific directions for bed bug control. Spray or dust beds (slats, springs and frame) and other hiding places about the room.

Because it is impossible to penetrate all hiding places, control is usually not immediate. A few living bugs may be seen for a week to 10 days after application. After 10 days, a second application, equal to the first is necessary to kill the just hatching nymphs. The pesticides used for bedbug control have a short residual life and so this second application is always needed. For heavily infested areas, it is recommended that a commercial pest control operator be consulted to control the infestation.

Always read and follow carefully the instructions on the container label.

Related Publications

Bed Bugs – Insects in the City

Bed bugs: Do-it-yourself control options – Insects in the City

 

 

Bugwood Images