Numerous arthropod species establish nests or burrows within soil beneath the ground’s surface. Numerous ground spider species are known for frequently establishing subterranean burrows in residential yards, and several wasp species, particularly the German yellow jacket, prefer to construct subterranean nests as opposed to aerial nests. Occasionally, wasp nests are found attached to elevated areas on the exterior walls of houses, such as beneath eaves, but a lack of such nests does not mean that a property is free of subterranean yellow jacket nests.

Due to the relatively warm environment below the ground surface, cockroaches and flies become particularly abundant in sewers and septic systems during the colder months, but both of these insect groups dwell in sewers all year round as well. This is because roaches and flies rely on rotting organic matter in order to reproduce. Therefore, roaches and flies proliferate at an extremely rapid pace in sewer systems. During heavy storms, flash floods and spring snow melts, the rising water level in sewer caverns and within ground burrows on lawns prompt roaches and spiders to seek agreeable shelter within homes. However, sewer-roaches and burrowing spiders invade homes in very different ways during and after storms.

While both American and Oriental cockroaches inhabit sewers in massive numbers, the latter species is a more common home invader during storms. When sewers become flooded during heavy bouts of rainfall, Oreintal cockroaches seek higher ground by traveling through sewer pipes and into homes. Many residents have claimed to find roaches emerging from their sink, bathtub and basement drains during storms. Oriental roaches are also abundant in crawl spaces where they are known for traveling through utility gaps and into homes via the outside surface of pipes during rainstorms. While ground dwelling spiders do not specifically seek indoor environments during rainstorms, they do abandon their burrows in order to seek higher ground where they often encounter and take advantage of entry points on the exterior walls of homes. Ground dwelling spiders frequently seek protection from rainfall in crawl spaces, behind window shutters and siding, beneath drain spouts, and against a home’s foundation where eaves block rainfall. From these locations, spiders find easy access indoors.

Have you noticed that arthropods become more abundant within and/or around your home following storms?