Lady beetles out in numbers
July 9, 2018
Walking down the street recently, I saw something wonderful and unusual. There were lady beetles in all stages on sunflowers and weeds along the ditches. I've seen all stages of this beneficial insect separately before, but never at once on one plant and in such great numbers. I was thrilled!
In North America, most people call this family of small beetles ladybugs. They're known as ladybirds or lady beetles in Britain and other English-speaking countries. However, entomologists prefer ladybird or lady beetles because these insects aren't true bugs, which are a class by themselves. There are 6,000 species currently identified worldwide.
Most of this family are beneficial eating aphids, scale, mites, mealybugs and other sap-sucking insects. A single lady beetle may eat 5,000 aphids in its lifetime. Some species attack caterpillars or other beetle larvae. They can even cannibalize their own species when other food sources are limited. They're usually found on plants that harbor their prey. While they're preyed upon by birds, frogs, wasps, spiders and dragonflies, they're protected by a smelly noxious fluid they exude out of their joints when they're disturbed. Their bright color can help predators remember this and avoid them.
Lady beetles come with a great variation in color patterns, from the traditional orange with small black spots on wing covers to yellowish, red or black, sometimes with spots, sometimes without. The color and spotting are determined by species. They're round to oblong in shape.
Adults lay eggs in clusters, usually within aphid or other prey colonies. Eggs can hatch in three to four days. The larvae go through four instars over 10-14 days. An instar is a phase between two periods of molting. After the four instars, the insects pupate during which time they're inactive. After this stage, adults emerge from the pupal casings and can be weak and soft-bodied for several days. Finally, the adults are ready to reproduce. With warm weather, the adults can reproduce multiple times in a season. Adults often undergo a period of suspended development at the end of the season, overwintering in large groups (to stay warm) at higher elevations or under leaf litter, rocks, other debris or even in buildings. Their total life span ranges from one to two years
To conserve these beneficial insects, first recognize their different life stages. Try to avoid insecticides. And count yourself lucky when they're around.
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JoAnne Skelly is Associate Professor & Extension Educator, Emerita, University of Nevada Cooperative Extension. She can be reached at firstname.lastname@example.org.