University of Illinois Extension

Ladybugs

Is your house being overrun with orange beetles? Many people are having this problem, noted a University of Illinois Extension horticulture educator.

"There are several thousand species of ladybugs or ladybeetles or ladybirds as they may be called, depending on where you live and what your mom called them," explained Jeff Rugg. "Some are what horticulturists call beneficial insects. They eat aphids, mealybugs and mites that are eating our plants. Some ladybugs are pests, because they also eat our plants.

"Most likely, the one trying to get into your house is the Asian ladybug."

In typical human fashion, it was decided a few years ago that if some beneficial ladybugs were good, then more would be better.

"I do not know why it was decided that none of the 400 native species of ladybugs was suitable, but someone thought it was better to release ladybugs from Asia and Australia into the United States to control aphids on soybean crops," he said. "Thankfully, they have not become direct pests themselves, but they have become a problem."

They were released back in the 1970s and 1980s in southern areas of the states and they are spreading west. They reached the Midwest several years ago and are not stopping here.

"The problem with them is that they are doing too well," said Rugg. "The native populations of ladybugs are declining to the point of extinction in areas where the Asian ladybugs are thriving."

Insects over-winter in different ways -- some as eggs and some as larvae. Ladybugs spend the winter as adults. They get together in large groups that use their own body heat to stay warm. The native ones tend to get together in piles of mulch or in hollow trees and logs. Some gardeners put up ladybug houses in sheltered locations in hopes of attracting native ladybugs to their gardens. The ladybugs find each other using pheromone scents. Special cards with the pheromone scent on them can be used to attract ladybugs to the houses.

"Having ladybugs spend the winter in your garden means an earlier start on getting rid of bad bugs next spring," he said.

In Asia, the Asian ladybugs over-winter in cracks in cliffs. Since there are more houses than cliffs in the United States, they think that a house is a good place to spend the winter. They find a crack under the siding or along a window frame. As more come, they leave more pheromone scent and so even more come. Sometimes the crack leads all the way into the house and they find their way indoors.

"Vacuuming them up is the easiest way to dispose of them," Rugg said. "If they are on the house walls outside, you can spray them with an insecticidal soap to kill them. The one possible benefit to having this problem is that it identifies that your house has a leak that lets in outside air. Caulking the leaky spot stops the beetles and saves you money."

If desired, they can be let back outside while the weather is above freezing. If they come indoors over the winter or in the early spring (too early to be let outside) they can be kept in the refrigerator for several months. They need to be kept in a jar with air holes. There should be a damp paper towel crumpled up in the jar. This will keep them from drying out.

The Asian ladybugs come in several orange and orange-red colors. People usually think the native beneficial ladybugs are bright, stop sign red with black spots. They also come in yellow, gray and black and with or without spots.

"If the ladybugs have stripes, they are probably Colorado potato beetles and since they are a pest, they should be killed," he said. "The adult and larvae of Colorado potato beetles are both voracious eaters of tomato, potato, eggplant and petunia plants.

"Green ladybugs are not ladybugs, but are probably the adults of northern corn rootworm or cucumber beetles. Both are serious pests that should be killed."

Native ladybugs can be picked up by hand and will not bite or cause a stink. Asian ladybugs can secrete a yellow liquid that does stain and smell.

"Asian ladybugs can give you a taste test to see if you are edible, and the bite is painful," said Rugg.