April's Ag Advice by April Borders The weather is starting to cool down and with the cooler weather we see those outdoor pests starting to try to move indoors. One insect that is becoming a nuisance for the homeowners is the Asian lady beetle.
The Asian lady beetle has been working hard this year feeding on the pests in the farmer's fields. Asian lady beetles are beneficial insects because they feed on aphids, scale insects and other soft-bodied arthropods that infest plants. These beetles have been quite numerous for the past two years because of the increase in numbers of the soybean aphids, a new pest of the soybeans in South Dakota.
Asian lady beetles are the main predators of soybean aphids in the fields during the growing season. Both adults and immature Asian lady beetle eat hundreds of aphids each day and keep the soybean aphid population in check.
Asian lady beetles look similar to our ordinary lady beetles except they like to congregate in large numbers inside our homes and buildings in the fall as they search for an overwintering site. Asian lady beetles are yellow to orange in color, about a quarter-inch long and 3/16 of an inch wide. A black "M" marking on their thorax or second body segment is a sure sign that you have Asian lady beetles.
The number of black spots on their wing covers can range from zero to 19. Asian lady beetles are also known as the multicolored Asian lady beetle, Halloween lady beetle, Japanese lady beetle, or imported lady beetle.
If disturbed or agitated, the Asian lady beetle may also excrete a yellow fluid that may stain carpets and walls. Otherwise they are not a damaging insect if they get indoors. They do not destroy wood or any structure in buildings, nor do they bite humans or pets on purpose.
They do, however, like to enter buildings only because they are seeking shelter. They do not feed or reproduce indoors. Beetles that overwinter successfully will leave their overwintering sites in early spring to start looking for their prey and to reproduce in the fields.
Asian lady beetles were imported from Asia by the United States Department of Agriculture to control aphids and scale insects attacking pecan trees and many other plants in the southern and eastern United States from Mississippi to Maine. Importation and release started in 1916 and continued until the early 1980s. No releases were made in South Dakota.
Entomologist Robert Kieckhefer made the first record of Asian lady beetles on South Dakota in October 1996 in Brookings. A single specimen was collected. Entomologist Louis Hesler from the U.S. Department of Agriculture's Agricultural Research Service subsequently surveyed and found significant numbers of the Asian lady beetle from several South Dakota counties during the 2000-2001 seasons.
Asian lady beetles are probably present wherever soybeans are grown in South Dakota. The soybean aphid was first found in South Dakota in Brookings in September 2001.
Since the Asian lady beetle is a beneficial insect, we should be more willing to tolerate them in our homes and buildings in exchange for their good work in our soybean fields. Dr. Mike Catangui, SDSU Extension Entomologist, encourages homeowners to conserve these insects.
Lady beetles found indoors can be collected using a vacuum cleaner or broom-and-dustpan. Collected beetles can then be released outdoors away from the house. Catangui suggests chemical insecticides are not necessary against Asian lady beetles. In the long run, preventing entry into homes may be the best way of controlling Asian lady beetles and other insects.
If you would like to see a picture of the Asian lady beetle and learn more about their biology visit Dr. Catangui's web site at: http://plantsci.sdstate.edu/ent/entpubs/alb_SD.htm
Also just a reminder to continue to protect yourselves while outside from mosquitoes by dressing appropriately and using personal repellents like DEET products. West Nile transmission season will continue until an area experiences its first hard frost, which is a temperature of 28 degrees F or less.
Until then we are encouraging people to take anti-mosquito precautions. If you have any questions or concerns please feel free to contact the Extension Office at 677-7111.