At different times of the year various insects which are not normally indoor pests may enter homes. These seasonal invaders are not usually serious pests and long term infestations rarely occur. However, large numbers of insects moving into structures are normally unwelcomed. This fact sheet will help you understand three common seasonal invaders: lady beetles, clover mites and boxelder bugs.
Lady Beetles
Multicolored Asian Lady Beetle
©Scott Bauer, USDA Agricultural Research Service, Bugwood.org
In the fall, large numbers of lady beetles or ladybugs may be found around homes. These ladybugs are most often the multicolored Asian lady beetle. They are about 1/3 inch-long, and yellow to orange in color, with or without black spots on their bodies. They often congregate on the sunny sides of buildings. If they get indoors, they can become a nuisance. While these beetles do not bite, sting or carry human diseases and do not reproduce indoors, their sheer numbers can be annoying. At the same time, they are considered very beneficial in the garden and yard because they feed on harmful aphids and some scale insects that can be serious plant pests.
Adult lady beetles often cluster together in October and November to survive the winter in sheltered locations. When a few adults find a suitable spot, they release a chemical that attracts others to the same location.
To reduce these beetles in and around homes, vacuuming is generally the best method. It is important to vacuum them quickly as a few can attract others. If a clean vacuum bag is used, it can be stored in a sheltered area outside and they will emerge in the spring to feed on garden pests.
Clover Mites
These pinhead sized mites feed on grasses and other plants around structures. Clover mites are rusty red in color and can cause parts of a lawn to look bronze in appearance when many mites are present. Their numbers are usually greatest in the spring when daytime temperatures are below 70̊ F. This is the time they often move into structures. They do not bite people or pets but they can stain fabrics or walls if they are squashed.
Clover mite control is usually not difficult. If possible, remove grasses and weeds from around the foundation of the infested structure. Areas cleared of grass can be replanted with plants that are not appealing to clover mites such as marigold, zinnia, rose, chrysanthemum, petunia or shrubs like spruce and juniper. Entry points like cracks and crevices that allow mites to enter building should be caulked and sealed. If mites do enter, they can be vacuumed using a soft brush attachment to avoid crushing them. Once vacuumed, place the bag in outside trash.
Boxelder Bugs
The common name reflects that this insect is a pest of seed-bearing boxelder trees. These insects can also be found on other trees such as maples. Boxelder bug adults are about ½ inch and mostly black with several reddish lines, especially along the edge of their bodies. Immature boxelder bugs are smaller and bright red with only patches of black. Like lady beetles, boxelder bugs often cluster together in the fall to survive the winter in sheltered locations. Often this means inside a home.
Boxelder bugs do occasionally bite people, causing some skin irritation. But the biggest problem from this insect is the red stain their droppings can cause on carpets and fabrics. As with other seasonal pests, the best way to prevent invasion is to caulk exterior cracks and other openings that boxelder bugs use to enter buildings. Sometimes, boxelder trees can be removed, but keep in mind that the infested trees may not all be on your property. Inside structures, boxelder bugs can be gently vacuumed with a soft brush attachment and discarded in outdoor trash.
Chemical Control
Pesticides are not recommended for any of these seasonal pests unless the temporary annoyance becomes intolerable. Sprays should be applied to outdoor areas where the insects or mites enter the structure or collect in large numbers. If large numbers of insects are killed, be sure to remove them. Dead insects, especially in wall voids, can attract more serious pests. If treating plants, make sure the product you use will not harm them and is labeled for the area and pest you are spraying. Remember, seasonal pests may come from areas outside of your property that you cannot spray.
Originally published 12/98
