House Pests in the Fall: Hobo Spiders, Yellow Jackets Not a Threat if Left Alone

When fall arrives people seem to find more spiders in the house, including the dreaded hobo spider. “There is an undeserving hype about hobo spiders,” said Art Antonelli WSU Extension entomologist.

Hobo spiders (Tegenaria agresti), one of three common house spiders species found in Washington, are known by people to bite and cause wounds that won’t heal. Antonelli said that the wounds are most likely caused by bacteria rather than spider bites, “There are very few documented cases of hobo bites causing this kind of lesion,” he said.

Although hobo spiders might be found more often indoors in the fall, when males are more active because of the mating season, Antonelli also said that spiders do not go into houses because they are warmer than the outside temperatures. “Spiders will not deliberately seek open spaces. There is not enough food in a house and people kill them; being indoors is a disadvantage for the spiders.”

If people find a Hobo spider in the house, they should check openings and eliminate entrance pathways for spiders. Spider bites typically occur when the spider is squeezed by picking up a piece of firewood or when putting on an article of clothing where the spider is located. If you think you have been bitten by a hobo spider, you might want to seek medical attention. “When possible, collect the spider and have it identified by an expert,” said Antonelli.

European paper wasps and yellow jackets are another house pest that will become more of a nuisance in August and September, when colonies will become hungrier before the queens die and the colonies collapse.

Looking at the nests is a way to identify one species from the other. European paper wasps build nests where the cells are open and easy to see, while yellow jackets’ nests have only one opening and are covered by paper. European paper wasps were introduced in Washington around 1998 and are now the only paper wasp in the state. They can become a real nuisance when they build their nests under patio furniture, in light fixtures, mailboxes, or under deck railings.

Antonelli said they will sting only if they are bothered. Yellow jackets, however, are more aggressive than the European paper wasps, especially in late summer or fall, when they can sting without being provoked.

He recommends leaving the nests alone in most cases, since both species are beneficial predators. If nests are in your line of normal movement or if there are children around, it might be a good idea to remove the nests. If the nests are in hard to reach spots in the house, Antonelli suggests calling a professional to have them removed. “Otherwise, plan your retreat well, make sure there are no patio furniture or toys in your way,” he said.