For weeks now, the insects currently clustering in homes here in the North East, are tiny Fall visitors called Asian lady beetles. These little uninvited guests, ranging in color from red to orange and yellow with black and white markings, are swarming to homes in preparation for the Winter conditions to come. Both our native red ladybugs and Asian lady beetles are in the insect family Coccinellidae, and although they can look alike, they have very distinct behaviors. The easiest way to tell them apart is to look for a distinctive white “M” on the beetles’ heads.
Similar to butterflies, ladybugs and lady beetles go through four stages before they complete their metamorphosis. They begin as eggs that hatch into larvae that resemble tiny spiny alligators. Then begin the pupal stage that lasts around two weeks. In their final phase, they become adult ladybugs and their hidden wings appear. Adult ladybugs have a smooth dome shape and their forewings are protected by an outer shell called elytra. Underneath the outer shell is a pair of thin hind wings that unfold at a speed of 0.1 seconds and are significantly larger than the ladybug’s body. Once unfolded, ladybug wings move at a rate of 85 beats per second.
Here in the Adirondacks, native ladybugs, with their round bodies, red wings with a few black spots, are harmless insects that feast on garden pests like aphids. They stray from crowds so they rarely gather together in large numbers and, never go looking for a winter home indoors and become unwanted company.
The multicolored Asian lady beetles love being with other beetles in great numbers, especially around warm, reflective objects such as flashing on gable ends, windows and metallic vents. These beetles don’t frequently bite, but when threatened or startled, they will deposit a foul smelling, yellowish fluid called hemolymph in a process called reflex bleeding. This liquid is the insect equivalent of blood that they are able to release from between the joints of their legs as a defense mechanism.
So how did these foreign creatures get here, being natives of eastern Asia? There are some recordings that Asian lady beetles existed in the United States as far back as 1916, introduced by farmers and gardeners alike to control pests that could decimate crops. These beetles are also recorded as being introduced into the United States by the U.S. Department of Agriculture as a biological control agent. They originally released in Pennsylvania in 1978 and 1981, but the first overwintering beetles were not recorded until 1993. This beetle’s recent population increase in Pennsylvania and northern states may not have resulted from the earlier USDA releases, instead are thought to have accidentally been brought by an Asian freighter docking in New Orleans.
No matter the source of these little creatures, it appears they are here for the long run. Instead of heading south for the winter, ladybugs and lady beetles living in colder climates enter diapause, a type of insect hibernation. When the aphids begin to disappear, ladybugs are alerted that winter is coming and flock together to reproduce right before entering hibernation. During this period, which can last as long as nine months, they live on their fat reserves, which hold them until spring when insects become plentiful again. If you’re a bug lover like I am, its hard and potentially messy to kill these little creatures. If these guests insist on coming indoors, the most humane thing you can do to uninvite them, is to sweep or vacuum them up and release them back to nature. When people keep their homes nice and warm, the lady beetles won’t become dormant which means they are going to get hungry, not be able to find food and starve to death. Outside in a natural setting that gets colder and stays cold, they will stay dormant for the entire Winter. Asleep until Spring, when the circle of life continues.
Images courtesy of the author
they have been swarming to my home since around 1982 every fall in an old porch on the front of the house. In fact 15 years ago i redid that porch and discovered that the un-insulated walls were about 2 feet deep inside with dead asian beetles and litterally was tossing about 15-5 gallon buckets of dead beetles into my compost pile. they still come every fall by the thousands and i dont mind them over-wintering for my garden in spring.
Nice and timely story about these insects. “Ladybug” is just a general name for beetles in the ladybug family, so it’s fine to refer to Asian lady beetles as Asian ladybugs. That’s what most people do anyway.