Back in the late 1950s, I visited the Southwest for the first time with my parents, who bought me a little booklet on the common venomous critters of American desert habitats. First published in 1947, this gem was sort of a less showy, regional cousin to Herbert Zim and Clarence Cottam’s blockbuster Golden Nature Guide “Insects” (Golden Press, 1951). Inexpensive and concise, both were destined to become postwar classics that have been indispensable to three generations of budding naturalists. My copy of the desert animal pamphlet was in its seventh printing and cost 50 cents.
It had a fairly extensive section on black widows, for which its control recommendations included brooms, blowtorches (no kidding), and a 5-10 percent solution of DDT. Recluse spiders (Loxosceles spp.) had not yet been discovered by the talent scouts who subsequently promoted them to the public-menace rock star status they enjoy today.
Since 1960, the booklet was reprinted 17 more times, sold 300,000 copies and finally was totally redone in 1995. I picked one up in 2008 for $5.95 and discovered that, in keeping with the changed zeitgeist, the sections on control are now called “prevention.” Loxosceles has joined the rogue’s gallery, and this, in its entirety, is what the manual has to say about their management:
“Brown spiders are not in any way aggressive toward humans and most bites occur when the spider is trapped in clothing, bedding or against some substrate. Watchfulness and basic precautions — shaking and checking bedding and clothes before use and looking before putting your hand under or into something — best prevent contact with brown recluse spiders. To control any spider population, keep debris and litter away from your house and yard. Make sure doors and windows are tight fitting with good weather stripping, and that any other openings are closed or fitted with a fine mesh screen.”
I’ve chosen this example because the book remains one of my favorite references and, in general, has so much going for it. But this passage illustrates a distinctive category of pest control advice that has become ubiquitous in recent years, and which I classify as “upbeat preventive recommendations by writers who have never had the problem.” Or to be fair, writers who may indeed have experienced the issue firsthand but really don’t consider it to be much of a problem in any case. If I were more curmudgeonly, I’d call this segment of text irresponsible. Since I’m not, I’ll just label it and the genre it represents as “whistling in the dark.”
SOME BACKGROUND. An enormous body of technical literature on Loxosceles has repeatedly confirmed that these formidable invaders are almost impossible to keep out of normal structures with normal sorts of yards and normal sorts of surrounding habitat. Advice on walling yourself in is good as far as it goes, but the shells of typical buildings are simply too porous and the spiders too numerous and too adept at finding the crevices for a practical level of sealing to be a particularly effective methodology in many areas.
Even more to the point, it’s not as if a structure starts out pristine and then comes under pest attack as soon as it’s occupied.
Inward leakage from enveloping population reservoirs begins early in the construction stage for a multitude of synanthropic species.
Pest after pest, from rats to roaches, the IPM advocacy literature has fallen into the habit of extolling prevention with far too few caveats as to its limitations in built environments that are overwhelmingly permeable, sanitarily challenged and ruled by remorseless entropy.
Are there things you can do, beyond that quoted paragraph, to minimize recluse populations in your living space? Of course. They involve both repetitive non-chemical options (such as sticky traps liberally placed along walls) and repetitive chemical ones (such as sprays or dusts in dark, remote locations where the spiders prefer to live).
I wouldn’t recommend either of these if you have a cat. But even if you don’t, and this happens to be an issue of concern, and you wish to concentrate on a preventive approach as much as you can, don’t expect that tidying up the debris and litter, or obsessing about the weatherstripping, is going to provide the level of relief implied by the desert critters booklet. For that, you need to move away from habitats where the spiders are abundant..