DALLAS - Got ladybugs in the house?
If so, don’t panic, said a Texas Cooperative Extension expert.
Seen in the worst light, the brightly colored beetles are merely a nuisance. In the best light, they are a beneficial insect that eat harmful plant pests, said Dr. Allen Knutson, Dallas-based Extension entomologist.
“The beetles are very beneficial as they eat the aphids that are common pests in pecan trees, roses, crepe myrtle and other shrubs,” he said. “They also feed on aphids in cotton and some other field crops.”
For unknown reasons, ladybug numbers have been large in the last few years. This time of year, as temperatures cool, the beetles seek warm, dry, protected areas to hibernate. In the wild, they migrate to crevices in rocks and caves. But in populated areas, they find house eaves and attics made to order. When ladybugs gather in large numbers — sometimes in clumps of thousands some eventually will find their way into the living area of the house.
The ladybugs that prefer to hibernate in houses are most likely an Asian import, Knutson said. Native species of ladybug prefer to hibernate outside, in garden mulch or under leaf piles, for examples.
Neither Asian or native ladybugs are harmful to humans. They do not sting or bite. Inside the home in large numbers, however, the Asian beetles can stain draperies and clothing.
“The beetles have a defense response called ‘reflex bleeding’,” Knutson said. “When they’re disturbed, small droplets of blood are released at the leg joints, which apparently defends the beetles against attackers.”
Any rough handling of the beetles triggers this defense mechanism, Knutson said. Some people resort to spraying outside their house; some treat the inside. The pesticides work; they kill the beetles. But Knutson doesn’t recommend their use, particularly inside the home.
“Hundreds of dead beetles can accumulate in wall voids and attics, creating a foul situation,” he said.
Vacuuming is the preferred method of ‘de-ladybugging’ the home, Knutson said. Once vacuumed, the beetles can either be relocated to or disposed outside.
As for outside and attic-confined beetles, the problem will eventually just fly away.
“As temperatures warm in the spring, the beetles become active and find their way out of the house. Other than being a serious nuisance and the possible staining problem, they do not harm people or structures,” he said.
No one knows for certain how Asian ladybugs found their way to North America. Because they prefer trees more than the native ladybug species, the U.S. Department of Agriculture tried to establish them in the United States to protect pecan and ornamental trees. Though the USDA was persistent, trying various methods from the 1920s to 1980s, the official word is that their efforts failed, Knutson said.
In the United States, the beetle was first found in large numbers near New Orleans in 1988.
“Since none had been released nearby, many believe the beetles arrived as stowaways on ships coming into the port at New Orleans. If so, they arrived as did the fire ant, on-board ships entering a southern port,” he said.
From populations in New Orleans, the beetle spread and was first recorded in Texas in 1992.
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