Bulletin 1139 - April 1996, Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, The University of Georgia College of Agricultural and Environmental Sciences and the U.S. Department of Agriculture cooperating.
Native and exotic species of lady beetles are some of our most successful predators and are highly beneficial. There are approximately 480 species in the family Coccinellidae in North America. Lady beetles are predators in both the immature and adult stages and devour their prey directly. Although lady beetles are not particularly picky about what they ear, they are most frequently found feeding on aphids, mealybugs, scale insects, mites and other soft bodied insects.
For more than 100 years, scientists have searched for exotic species of lady beetles to introduce into the United States for the control of specific pest insects. Six species of exotic lady beetles are now established in the eastern United States including the sevenspotted lady beetle (Coccinella septempunctata), the multicolored Asian lady beetle (Harmonia axyridis) and Coccinella undecimpunctata, Propylea quatuordecimpunctata, Hippodamia variegata, and Harmonia quadripunctata. Where present, these species are welcome residents as they suppress pests in a wide range of plants including vegetables, apples, cotton, corn, pecan, cereal crops, wheat, tobacco, pine trees and ornamental plants.
Despite the obvious benefits of lady beetles, some people consider them pests. As winter approaches, large aggregations of adult lady beetles (particularly Harmonia axyridis) can be found on outside windows, doors, walls and porch decks looking for a suitable overwintering site. They are particularly attracted to light-colored structures with sunny southwest exposures. On occasion, the beetles attempt to overwinter indoors. As temperatures warm in the spring, the overwintering beetles become active again, leave their overwintering sites and disperse to find food. During these periods of aggregation and dispersal, people often complain that the beetles become a serious nuisance pest. Remember that lady beetles do not bite, sting or carry human diseases. Nor, do they feed on wood, clothing or human food or reproduce inside the home.
Prevent entry of lady beetles into houses, storage buildings, attics and other structures by sealing up cracks and crevices in these structures. Use a good quality silicone or silicone-latex caulk to seal cracks and crevices around windows, doors, siding, utility pipes and other openings. Replace or repair damaged door and window screens. Install insect screening (20 mesh maximum) over attic and exhaust vents to prevent their entry.
Remove lady beetles inside the home with a broom or dust pan or the vacuum cleaner with the crevice tool attachment. A trap for ridding houses and other structures of Harmonia axyridis lady beetles is under development and will soon be available for use. Research reports document capture of essentially 100 percent of all active beetles within a room or attic where the trap is operated. Release captured beetles outdoors in sheltered areas.
Avoid killing beetles found indoors by spraying them with an insecticide or squashing them. Handling lady beetles or picking them off walls or furniture can stress the beetles. Stressed beetles secrete an orange substance from the joints in their legs that, though harmless, can stain walls and fabrics. In highly sensitive areas such as hospitals, health care facilities, food processing plants and electronic productions facilities, invasions of lady beetles can not be tolerated. Prevent entry into these areas through screening and caulking cracks and crevices. When beetles cannot be successfully excluded through screening and caulking, insecticides can be applied to provide temporary control. Products containing carbaryl (Sevin)TM or chlorpyrifos (Dursban)TM sprayed on the aggregations of beetles or applied to the harborage site will temporarily control beetles found on the outside of structures. Products containing pyrethrins may be used in addition to vacuuming to remove beetles found inside structures.
Lady beetle: friend or foe? Once a person understands the beneficial aspects of the beetles, there is little doubt that the benefits far outweigh the nuisance aspect of their overwintering behavior.
For More Information:
The Bugwood Network - The University of Georgia
College of Agricultural & Environmental Sciences
Warnell School of Forestry & Natural Resources
Page last modified: Monday, April 29, 2002
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