Fall nuisance invaders on the move

As harvest begins and other plants in the landscape senesce, many insects and arthropods move to find overwintering habitat. Sometimes these animals seek out shelter in cracks and crevices of human structures such as houses and storage buildings. Common invaders include boxelder bug, lady beetles, millipedes, crickets, clover mite, pine seed bug and spiders. Pests enter structures accidentally and are generally harmless to people and property. Invaders do not sting, carry disease, reproduce or feed on people, pests, houseplants, stored food products or furnishings. Sometimes, invaders can stain fabrics, secrete foul odors or trigger allergens.

The preferred management for accidental invaders is exclusion, or to prevent them from entering the structure. Make sure windows and doors fit tight; replace screens on windows and vents; seal other openings around the foundation, pipes, wires and chimneys; and keep siding, eaves and soffits in good condition. A plant-free band of rock or inorganic materials that extends 2-4 feet from the foundation will provide an unattractive barrier for insects and spiders. Remove any pests that enter a structure with a vacuum.

Pesticides use for fall-invading pests is a less desirable option, as these products are short lived and can have non-target risks. Pesticide barriers can supplement exclusion tactics but multiple treatments may be necessary depending on pest abundance. Treat the southern and western sides of structures, where insects are most common. Insecticides must be applied before pests begin to enter buildings to be effective (e.g., September to mid-October). Direct application of insecticide to pest clusters outside of buildings may reduce the outdoor population and limit the number that will get into the house. Begin spraying as the insects congregate in late summer and repeat as necessary.