Callaway County

November 2000

Fall Nuisance Insects

Nuisance Insects
November 1

Jim Jarman
573 - 642 - 0755
jarmanj@missouri.edu

Again this fall the Asian multicolored lady beetle is the most common insect trying to use our homes for shelter. Other common names for this insect include the Halloween or pumpkin lady beetle (from the time of year it swarms and its color), the Japanese lady beetle (from its country of origin), and simply the Asian lady beetle or bug. Besides the variations in color, they may have from 19 to no spots.

The Asian multicolored lady beetle (AMLB) is a beneficial insect. It eats various soft-bodied pest insects such as aphids, scales, spider mites and the eggs of insects. In Asia, it was primarily a predator of tree infesting pests. In the U.S., AMLB are known to prey on pests of maple, walnut, willow, rose, and other ornamentals and agricultural crops. Adults may live for 2 to 3 years. AMLB have almost eliminated the need to sprays for aphids in US pecan orchards. Each AMLB, trying to get into your home, is surely responsible for eating thousands of insect pests.

USDA studied it as a bio-control agent against tree and other plant pests. Releases of AMLB from Japan were made in California during 1916, 1964, and 1965 and in a dozen eastern and southeastern states in 1978 through 1982 and 1985. All this work was considered a failure until they were seen in the southern U.S. Sometime during 1992 or 1993 AMLB arrived in Missouri. The first complaints came late in 1993.

In Japan, the AMLB overwinters in caves. Our homes must be much more inviting than Japanese caves. Actually, they are attracted to light colors like whites, grays, or yellows. So, light-colored houses, especially on hillsides, alone, or around forests are extra attractive. Many may enter the living spaces though more may actually remain within the walls. Once the lady beetles enter the walls of a building through cracks and crevices, they may or may not proceed to the interior of the building. Most stay in the wall spaces. Although, on warm days during the winter and early spring, overwintering beetles in a wall space may become active. During their search for an exit, they may enter the home's living areas and become a nuisance. Warmer temperatures or lighting in the living areas may attract these active beetles as they try to get outside.

There are several other insects known to be a similar nuisance. Most of these pests are well known such as the boxelder bug, paper wasp, several different small weevils, house flies, and clover mites. Their common characteristic is they overwinter as adults. Unfortunately for them and us, they choose our homes for winter quarters. Homes are too warm and dry inside for insects to survive for very long.

The use of pesticides to control the AMLB and should be avoided if possible. Even if today's swarm is sprayed and killed, additional swarms usually continue until it remains cold. The best control is excluding them. The entry of numerous nuisance insects into a home signals the need for caulking and sealing of cracks and crevices around the home. If lady beetles and others can get in, so can those cold winter winds. Use a broom or vacuum cleaner to gather the beetles and release them outside. Try not alarming them during the clean up. AMLB may discharge a yellow defensive fluid when alarmed that may stain, and has an unpleasant earthy odor. If they are swatted or crushed, the odor and stain are more likely. The odor of AMLB has been reported to aggravate asthma. Lady beetles that enter living areas are typically attracted to light. A black light trap for indoor use to attract lady beetles and other flying insects was developed by USDA, Agricultural Research Service (ARS) specialists. The insects become trapped in a removable bag so the use of insecticide is unnecessary. The trapped lady beetles and others can be released outside. "Bug Zappers" are for use outdoors only so don't even think about that. Detailed technical instructions and diagrams for constructing the trap are available on an ARS web site in PDF file at: http://www.ars.usda.gov/is/pr/2000/001030.trap.pdf and at the Extension Center. Left over Halloween black light should be going on sale today. I am sure industrious readers can use one of these more economically and simply than the "detailed technical" trap instructions.

Information for this article is from Ben Puttler of the University of Missouri's Entomology Department, MU Guide Sheet 7368, and USDA's web pages on the Asian multicolored lady beetle.