Imagine my disgust when I walked out to inspect plant today after several days of rain to see this:
This coreopsis that I raised from seed last year was nearly completely devoured by leaf beetle larvae. I don’t know enough about insects to identify which species of leaf beetle it is but I am positive it is a Calligrapha. The damage is pretty devastating. The leaves are spotted with holes and very few leaves have escaped untouched. The interesting thing (Yes, I can find something interesting in this!) is that they are only on the coreopsis plants. I have several of them in our rain garden along with other plants like coneflowers, goldenrod (Solidago), butterfly weed (Asclepias), and some ornamental grasses but only the coreopsis plants received any damage. The picture above was the worst one damaged but all of them have seen damage. Coreopsis are generally pest free but apparently I have managed to attract one of the few pests that like them.
So how do I know it’s The Beetles (and their larvae)? Take a closer look at the damage and you will see the culprit. The little black larvae on the left has been caught red handed, feasting on foliage. I had no choice but to bring out the insecticidal soap. Hopefully I managed to eliminate them all but I’ll treat again in a couple days. I would love to wait for a beneficial bug to find them but by that time my coreopsis would be gone. Insecticidal soap should do the trick! I sprayed each coreopsis on as much of the leaf surface as I could making sure that the undersides were covered.
Coreopsis is a vigorous grower and should come back as long as the larvae stay away. At least the other plants didn’t look as bad as this one. If you see even one of these little insects eliminate it fast and watch out for more! I’m definitely not a fan of these beetles!