Northwest Exterminating has seen an increase in calls for spiders this year. No doubt that is not news to most of you. With the cold and wet Winter and the heat this Spring, spider numbers have increased at an alarming rate. What can we do? Is there an answer to help stem the tide of the unwanted visitors? There is but first a little background.
Fear of spiders (arachnophobia) is consistently one of the most common fears. Possibly dating back to antiquity (remember Little Miss Muffet?). Most entomologists will tell you the fear is basically unfounded and the spider just suffers from bad PR. Adding to the fear and confusion is the readily available Emergency Room diagnosis of “spider bite” for any bump, nodule or unexplained skin eruption. This not only is a nuisance but can be quite dangerous since the “official” diagnosis can often mask the true culprit sometimes a much worse malady such as MRSA.
There are over 40,000 species of spiders on our planet. Most are harmless and even beneficial, helping keep other pest populations in check. Spider silk is perhaps the strongest material on the planet and scientists are constantly trying to duplicate its tensile strength. All spiders are venomous, that’s how they capture and digest their food, turning the insides of the common pests into a soup, but most venoms will have little or no effect on humans. Possible medical uses for spider venoms are being investigated, for the treatment of cardiac arrhythmia, Alzheimer’s disease, strokes and erectile dysfunction.
Spiders use a wide range of strategies to capture prey: trapping it in sticky webs, lassoing it with sticky bolas, mimicking the prey to avoid detection, or running it down. Most detect prey mainly by sensing vibrations, but the active hunters have acute vision, and hunters of the genus Portia show signs of intelligence in their choice of tactics and ability to develop new ones.
The abdomen has no appendages except those that have been modified to form one to four (usually three) pairs of short, movable spinnerets, which emit silk. Each spinneret has many spigots, each of which is connected to one silk gland. There are at least six types of silk gland, each producing a different type of silk. Silk is initially a liquid, and hardens not by exposure to air but as a result of being drawn out of the spider.
Some spiders have a cribellum, a modified spinneret with up to 40,000 spigots, each of which produces a single very fine fiber that is combined into a composite wooly thread that is very effective in snagging the bristles of insects. Species that do not build webs to catch prey use silk in several ways: as wrappers for sperm and for fertilized eggs; as a “safety rope”; for nest-building; and as “parachutes” by the young of some species.
This doesn’t answer the question though, “How do we control them?”. Spider control is best accomplished through proper housekeeping, the strategic placement of products and reducing harborage and points of entrance. It’s impossible to keep all spiders out, except in the Space Shuttle, but a great reduction can be achieved. Here are some steps to take:
- Remove all extra boxes, bags and containers from off the floor
- Be thorough in removing any and all webs
- Allow items that must be on the floor or shelving that sits on the floor to have some space from the wall (at least 8”)
- Keep lights off the building if possible, for security you can have a light shine onto a building
- Reduce all vegetation at least 18” from the building outside
- Seal all areas around windows, doors and other entrances into the structure
- Reduce/eliminate standing water
- If you can capture the spider and set it free so it can continue to protect your building
- Treat the areas the spider may hide or build a web with a light fan spray covering the corners of the area. Make sure to treat into any cracks and crevices adjacent to the webs.