Q: There are many insects visiting my pollinator garden that look like yellow-orange versions of a firefly. Some of the petals are missing on those flowers. How do I keep them from chewing my plants?
A: These beetles are innocent bystanders and are not the cause of damage, even though that’s where you see them most. These are soldier beetles, and although beetles have chewing mouthparts, soldier beetles are primarily pollinators as adults and predators as larvae.
The pollen and nectar in the blooms of plants in the aster, carrot, and milkweed families are favored, and where you’ll often find them, dining solo or mating. Adults can also eat soft-bodied insects, which include aphids and caterpillars.
Occasionally, you may find a soldier beetle clinging to a flower head by its jaws and dangling with wings spread, dead. This is a work of an entomopathogenic (insect-infecting) fungus, an example of how natural factors impact insect populations, both for species we consider pests and those we consider beneficial.
Soldier beetle larvae hatch from eggs laid in the soil and feed on the eggs and larvae of other insects they encounter. Their prey can include grasshoppers and caterpillars, and these garden helpers are great for suppressing pests like cutworms, corn earworms, and cucumber beetles. The larvae overwinter underground. To provide hunting grounds and shelter from the weather, do not remove the protective blanket of leaf litter and avoid tilling the soil.
If flower petals go missing, another culprit is to blame – probably a chewing insect like Japanese Beetles or Asiatic Garden Beetles, but in some cases, a slug or snail. (Deer and rabbits tend to eat the entire flower head, so their damage tends to be more extensive than just nibbling around the edges.)
Missing its petals doesn’t necessarily ruin a flower’s wildlife value. Tolerate the damage if you can, or find a chemical-free way to discourage feeding. For example, flowers grown for cutting (like dahlias or mums) could be enclosed individually in small mesh bags before they open fully to exclude pests. However, that would deny pollinators access, too.
By Miri Talabac, Horticulturist, University of Maryland Extension Home & Garden Information Center. Miri writes the Garden Q&A for The Baltimore Sun and Washington Gardener Magazine. Read more by Miri.
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Interesting article.
Thank you!