We just bought a house that was in foreclosure and empty for several months. We found an awful lot of spider webs and a few spiders but I’m worried about spider eggs that might still hatch out. What should we do to prevent that? K. B., Hampstead, NH

What you do now might depend in part on whether or not you have already moved belongings into the house. An empty house will be much easier to inspect and treat, if necessary. Empty or not, give Colonial Pest a call for a professional inspection. Besides spiders, the house may have other pest issues so now would be a good time to address those as well.

Web spiders are especially difficult to kill with pesticides since they spend much of their time in their webs. They do not walk on surfaces where the pesticides have been applied and they don’t ingest pesticides by grooming themselves as insects do.

A VACUUM OR DUSTER IS AN ALL-PURPOSE TOOL

The best controls for spiders are prevention (including prevention of the insects they feed on) and use of a telescoping-handled duster brush or vacuum to remove spiders, webs, and egg sacs.

A spider’s egg sac is light tan or beige, globular, and papery-looking. Check out this blog, What Do Spider Egg Sacs Look Like?, so you know what you’re looking for. Many of the egg sacs that you find will be old and already hatched out but remove them all anyway. Chances are you’ve already taken a vacuum to the webs and maybe most of the visible egg sacs, but others could still be hidden. A single American house spider can deposit up to 17 egg sacs in her lifetime, each with 100-400 baby spiders.

Because spider egg sacs are tucked away in corners and hidden under objects, if you don’t bend down and look at the bottom sides of furniture and other items, you will miss most of them. Even if your house was emptied of furnishings, you should still look for hidden egg sacs under built-in shelves, under fireplace mantels, under window ledges, in closet corners, in kitchen and bathroom cabinets, and in any other dark, secluded areas. Simply vacuuming up the egg sacs and disposing of the vacuum contents should do the trick as long as you prevent new invasions.

PREVENT A RETURN OF SPIDERS IN THE FUTURE

Since spiders prey on household insects and other arthropods, anything you can do to pest-proof the house and keep other insects out will help reduce the spider population. Make sure windows and vents are screened and that doors have weather-stripping and thresholds. Gaps around garage doors are common pest entry points. Avoid using bright exterior lights that attract insects. Ask us about an exterior perimeter pesticide treatment that will keep insects from getting inside. We do pest-proofing, too.

Also make sure that you don’t already have an indoor population of ants, flies, silverfish, or other insects that the spiders are feeding on. That’s also where a professional inspection for more than just spiders will help.

Remember that in the long run, getting rid of spiders usually has more to do with eliminating other insects that they are feeding on than with trying to remove the spiders themselves. Eliminating the prey will eliminate the spiders. For more, see How Can I Get Rid of Spiders in My Home?