Earlier this year an arborist brought me a branch from a sickly magnolia tree. The branch was covered with honeydew, ants, and strange sucking insects called tuliptree scales (see “There’s a sucker born every day”). In addition to the pernicious scales, my friend discovered several small, white wax-covered insects cavorting among the scales. In an attempt to rid his client’s pretty magnolia of pests he treated the plant with insecticide. The carnage was rapid and complete. As an aside, the arborist volunteered that he was curious about the identity of the white waxy bug. He believed it to be some type of mealybug, another plant pest. This teachable moment provided an opportunity to say “You fool! You just murdered one of Mother Nature’s masters of disguise."
That wasn’t a mealybug. It was the larva of a ladybug, one of the good guys. You should have left it alone.” My rebuke may have been a little extreme. The ladybug (a.k.a. lady beetle, lady bird beetle) larva, Hyperaspis, really looks much more like a mealybug than a lady beetle. Cases of mistaken identity surround this beneficial insect and I am certain that many of these fine beneficial insects are killed unnecessarily each year. The larva of Hyperaspis produces wax from glands lining its sides. This wax is more than a way to be styling. Studies of related species of waxy lady bugs reveal that the wax reduces the effectiveness of ants and other predators that might like to make a meal of a ladybug larva. In this way the wax serves much like the trash carrying lacewing larvae we met in “A wolf in sheep’s clothing”, April 10, 2006.
The adult Hyperaspis ladybug searches for prey near a mound of scale insects.
One fairly easy way to distinguish the larva of this beneficial ladybug from pesky mealybugs is to give it a little poke in the behind. Mealybugs tend to stay in one place and move slowly. Ladybug larvae usually amble away quickly when disturbed. Although the larva of Hyperaspis is deceptive, the adult beetle is easily recognized. It is a gorgeous black beetle. Its wing covers are adorned with two red spots. Some species of Hyperaspis have combinations of yellowish spots or stripes on their shell.
The waxy larva may eat several thousand immature scale insects during the course of development and the adult beetles consume many harmful scales too. During autumn, larvae complete development and become adults. By Thanksgiving, adults have departed scale-infested trees to spend the winter in protected locations beneath bark or in leaf litter on the ground. Next spring, they will return to your scale-infested trees and lay eggs that will hatch into stealthy fleece-covered larvae. Keep an eye out for these small masters of disguise and when you see them, do not spray them with insecticides. They are working for you.
References
To read a fascinating account of Hyperaspis lady bugs, please visit the following web site:
http://alembic.nal.usda.gov:8300/jag/v6/v6i5/060197/a060197.htm