For many people, the mere mention of a brown recluse spider (BRS) sends a shiver up and down their spine. This is because they have read about severe reactions or viewed horrific images related to BRS bites.
To the contrary, however, it's reported that more than 90 percent of BRS bites are medically insignificant. This does not mean that a person should be dismissive of potential effects, but rather, bear in mind that we do not have to run in fear.
Kansas State Extension entomologists report that there are 13 species of Loxosceles "brown spiders" in the United States. In particular, the brown recluse spider, L. reclusa, is the most widely distributed species.
All but the most western portion of Kansas is within what is considered their natural range. Evidently, Finney County is not out of their range as they are very common across the area.
Their native habitat is outdoors where they actively hunt for their food — preferably soft-bodied insects — during the evening hours. At the first light of day, they seek cover in secluded areas (under piles of debris, wood, logs, rocks, etc.).
Their outdoor habits follow them into man-made structures, and thus, they hide by day and hunt by night. Indoor haunts include dark, secluded areas such as closets, attics, cellars, basements, crawl spaces, venting systems and wall voids. They also seek out cluttered areas such as in boxes, papers, furniture, clothing, blankets, or simply any place providing cover.
Fortunately, brown recluse spiders are shy creatures (again hiding by day) and are not aggressive. They will only "defensively" bite if provoked. Such incidences are accidental encounters where "hiding spiders" are "pinched," such as when putting on items of clothing, thrusting hands into pockets and/or rolling over a spider while asleep. Accidental bites also may be incurred while unpacking storage boxes in which spiders have sought refuge.
The bite of a BRS may be painless (for instance, if one were sleeping). If awake, there might be a slight stinging sensation. What happens after the bite is dependent on several factors: the amount of injected venom, the sensitivity of an individual to the venom and a person's overall health.
Fortunately (as previously mentioned), most bites do not result in severe reactions. A localized reaction might be as simple as a small, ulcerous area requiring time to heal. A more severe localized reaction characterized by an expanding necrotic area might require surgical excision followed by a skin graft. The most severe case would be a systemic reaction with resultant symptoms such as jaundice, spleen enlargement, hemolysis and renal failure.
It is commonly accepted that many homes harbor brown recluse spiders. Introductions are achieved by spiders entering through openings such as structural cracks, ill-fitting doors and windows and vents.
People moving into newly constructed homes may introduce spiders in shipping boxes and crates or any items brought in from former residences. Once in, brown recluse spiders readily adjust to their new surroundings.
So is it "a grass spider" or a brown recluse? Brown recluse spiders vary in size: small juveniles (less than 1/4-inch leg span) to mature adults (when flattened out, a leg span exceeding two inches), as well as in the color of their legs and abdomens. But there is a very definitive dark, violin-shaped marking on the "head-end" of all brown recluse spiders. Another descriptor of the BRS is that they possess three pairs of eyes positioned in a semicircle pattern at the base of the violin.
Obviously a person should not pick up a live specimen in order to examine it. Rather, capture the spider in a container with a lid. Place the container in your freezer overnight. Then examine the "dead" spider.
So what should a person do if they know that there are brown recluse spiders in their homes? Remember that brown recluse spiders exploit secretive areas in the home that are confining and difficult to inspect (attic areas) or to which there is no access.
The use of sticky traps or mouse glue boards is a favorite tactic for ensnaring crawling critters (including brown recluse spiders). Preferably, place traps in "dark" areas that might provide favorable resting places for the BRS. Also remember that if you have pets, traps should be placed in out-of-bound areas.
There are a number of "homeowner" insecticides (registered for indoor use) which list "spiders" on their product labels. However, they provide but minimal control of brown recluse spiders. If directly sprayed, spiders may die. But remember that most spiders are hidden during the daytime when a person is most likely to apply insecticide sprays.
By the time the spiders emerge for their nighttime hunting forays, insecticide treatments will have dried, and spiders can cross treated areas with impunity.
Contracting the services of a commercial pest operator may result in better control of brown recluse spiders — not because they necessarily have superior products, but rather they are trained to take their time to be thorough in their work, and they recognize and treat areas that the homeowner might not have considered. But even their best efforts will fall short of eradicating brown recluse spiders. They are difficult to control, so plan on an on-going, long-term program.
More information on brown recluse spiders is available in Extension publication MF-771, Pests That Affect Human Health: Spiders and Scorpions. Extension publications are available in county Extension offices, or electronically on the K-State Web site.