By Margaret Murphy
Horticulture Educator for Chippewa, Dunn, & Eau Claire Counties
Soldier Beetles in the Garden
A wonderful thing about the community garden I garden in is that together with vegetables, garden plots are often peppered with an assortment of flowers. As I wandered through the garden the other day, I couldn’t help but notice how alive it was with the movement and sounds of pollinating insects as they made their way from flower to flower. One insect in particular caught my attention because it just recently showed up in noticeable numbers-the soldier beetle.
We usually see the goldenrod soldier beetle, Chauliognathus pennsylvanicus, also called the Pennsylvania Leatherwing. The adult goldenrod soldier beetle is dark yellow in color and reaches about ½-inch in length. It sports a black head with a black spot behind the head. It also has a black, oval-shaped spot on each wing cover. August and September are the months we see the adults most active in the garden.
Some gardeners may become concerned when they see a large number of these beetles landing in their garden, but soldier beetles are not an insect to worry about. In fact, they are considered beneficial.
Soldier beetles overwinter as larvae. In spring, they are found in moist soil or plant debris where they feed on insect eggs and larvae including those of some garden pests. Larvae pupate in early summer and adults start to emerge in late July.
Adults may feed on aphids and other soft-bodied insects but they mainly forage on the nectar and pollen of flowers. They can be seen flying from flower to flower and are considered a valuable pollinator. This time of year, flowers also serve as a place for soldier beetles to find a little romance with one another. It is not uncommon to find them mating on flowers. Females lay their eggs at summer’s end.
Soldier beetles protect themselves by secreting an offensive chemical to make them less appealing to predators. Their yellow color is also thought to act as a signal that says they don’t taste very good.
Soldier beetles are harmless to both plants and humans. They don’t damage flowers or sting or bite. As such, it is unnecessary to control them. They can be found on many different types of annual and perennial flowers. This year, I planted some Teddy Bear sunflowers, zinnias and marigolds, which seem to be a big hit with them. So, next time you are out in the garden, keep an eye out for goldenrod soldier beetles. And, if they accidentally make it inside the house, just help them back outside.