Frequently Asked Questions - BROWN RECLUSE SPIDER

Do brown recluse spiders exist in Nebraska?

Although they are more common in states south of us, they so exist here. They are not aggressive and people are rarely bitten, but it does happen.

What does a brown recluse spider bite do to the person bitten?

Some people may be bitten with little reaction. Others may show strong allergic reactions, itching, rashes, and even serious infection and flesh decay. However, sometimes other types of infections, bites, etc., are mistaken for brown recluse spider bites.

The victim may be unaware of the bite for three to eight hours, when the bite may become red, swollen and tender. Apply ice to the affected area and raise it. Seek medical attention immediately.

How are brown recluse spiders identified?

Color: light brown.
Size: body is typically about 1/2 inch long. Legs are relatively long. The complete size, including the legs, is about the diameter of a quarter coin or a little bigger.
Eyes: three pairs of eyes, one in the center and one pair to each side. Of course, if you are close enough to see the eye arrangement, hopefully the spider is either dead or inside a jar.
Marking: Brown recluse are often called violin spiders because of the violin marking on the cephalothorax (front body region). The base of violin covers the eyes and the body of the violin extends to the middle of the cephalothorax. The neck of the violin extends from there to the back of the cephalothorax. Caution! Some other spiders have what appears to be a violin shaped marking. Also, some brown recluse spiders, especially young ones, may not have the violin shaped marking.

What are some other characteristics of brown recluse spiders?

Although the females tend to keep hidden, the males are more likely to be seen. Although they may do more of their travel at night, they can be seen during the day.

They have small fangs and are unlikely to be able to bite through clothing. However, if they are inside shoes, gloves or other items of clothing, they may bite when the clothing is put on and the spider is under pressure.

Will someone identify a spider for me?

If you can capture a spider in a jar, you are welcome to take it to the extension office for Lincoln and McPherson counties for identification.

You can also buy some glue boards and place them in window sills and on the floor near the walls and see what you catch over a period of a few days. Use flat glue boards, without raised edges.You are welcome to bring in glue boards for pest identification.

How can I make my home less hospitable to brown recluse spiders?

• Brown recluse prefer hot, dry conditions, so lowering the temperature and raising the humidity may help.
• Locate and seal cracks and other openings that allow spiders and insects easy access to your house.
• Use weather stripping and door sweeps to keep out not only spiders, but insects, mice and cold drafts.
• Cover windows with tight fitting screens that are in good repair.
• Cover soffit and attic vents with screen also, to keep out insects and spiders.
• Keep trees and bushes trimmed so they are not in contact with walls and roof.
• Limit the use of white porch lights. Yellow lights are less likely to attract insects and the spiders that feed on them.
• An insecticide barrier around the foundation of the building may help, but will need to be reapplied as the insecticide breaks down over time. Use a product containing cypermethrin, cyfluthrin, bifenthrin, deltamethrin or lambda cyhalothrin, labeled for brown recluse spider control. Follow pesticide labeling carefully.

What are some other ways to limit my risk of bites?

• Don’t leave clothing lying on the floor.
• Remove bed skirts and see that sheets are not in contact with the floor.
• Keep clothing and shoes off the floor
• Shake out shoes before putting them on.
• Step on gloves before putting them on, to kill spiders that may be inside.
• Keep a space between furniture and the wall ;or curtains.
• Wear gloves and long sleeved shirt any time you handle boxes that have been in storage.
• Before moving boxes into your home, or from your home to another person’s home, take them outside and carefully inspect them for spiders and spider egg masses. By the way, other pests, such as cockroaches, are sometimes introduced into new areas by way of cardboard boxes, too.

What are some other things I can do if I have brown recluse spiders in my house?

Clean up spider egg sacks. The brown recluse sack is a mass of white silk, roughly circular, but flattened, and attached to a wall or other surface.

Caution: Sometimes cleaning up their webbing without killing them, makes matters worse, by prompting them to wander around in search of new places to build webs. People have been bitten during or after cleaning.

Place glue boards, available at hardware and department stores, around the house; plenty of them. As spiders are caught it can give a rough estimate of the magnitude of the infestation. A lot of the spiders will die in the process, too, so place a lot of the boards around. Place them along the floors where they meet the walls, especially behind furniture and in corners; and windowsills. Use flat glue boards, without raised edges.
Note: Glue boards also trap cockroaches, other insects, and even mice.

Many insecticides are ineffective against this spider. In fact, sometimes insecticides only make matters worse. That is because brown recluse spiders have been shown to actually prefer to feed on dead insects and spiders, so insecticide application can provide them with a feast!

Foggers (“bug bombs”) are not likely to be effective. In addition, they leave insecticide residues on all surfaces in the area and are flammable. They are not a good choice in most situations.

We recommend working with a pest control professional with experience in dealing with brown recluse spiders.

Keep dead insects and spiders swept or vacuumed up to reduce the amount of food available for surviving brown recluse spiders.

For more information see:

Brown Recluse Spiders in Nebraska, by Barb Ogg, PhD, University of Nebraska-Lincoln Extension in Lancaster County.

Brown Recluse Spider by Michael F. Potter, University of Kentucky Cooperative Extension Service.