Green cloverworm? - Ask Extension
I found this caterpillar eating the tender leaves of a plant (Persicaria tinctoria) I've grown extensively with no pest issues. The white stripe along...
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Green cloverworm? #831627
Asked May 23, 2023, 2:09 PM EDT
I found this caterpillar eating the tender leaves of a plant (Persicaria tinctoria) I've grown extensively with no pest issues. The white stripe along the lower side makes it resemble the green cloverworm (Hypena scabra), but I couldn't find any indication online that this species extends this far west/into Oregon or the neighboring states. The adult moth is totally nondescript to my eyes so I can't say whether or not I've seen it. I haven't purchased any gardening materials from non-local sources, though last fall I did get several straw bales from a local sustainably run farm that claims not to use pesticides on their large variety of crops. (I also found some unfamiliar fungus, possibly Sclerotinia, on the roots of plants that were heavily mulched with this straw, so I'm a little wary of it.)
Multnomah County Oregon
Expert Response
Hi Skye,
Sounds like you are growing interesting plants and have this pest caterpillar. Unfortunately, there are so many types of caterpillars that unless it is really distinctive or is on a plant I am really familiar with, I have a hard time to ID them from photos. If I have specimens to look at under my dissecting microscope, I can key them to family. Otherwise, the best way to determine the species is to rear a few specimens to adulthood, and the adults are much easier to ID to species.
That being said, I can tell that the caterpillar you found is not the green cloverworm (Hypena scabra). I can tell that by looking at the prolegs (fleshy leg-like structures on the abdomen). The majority of caterpillars, including the one you found, have 5 pairs of prolegs (4 pairs on the middle abdominal segments and one pair on the last abdominal segment). In contrast, the green cloverworm is one of the species with only 4 pairs of prolegs (3 pairs on the middle abdominal segments and one pair on the last abdominal segment).
If you continue to see more of these caterpillars feeding on your Persicaria tinctoria, you could pick them off and freeze or squish them to kill them. If there are too many to keep up with, you might want to try a spray containing Bacillus thuringiensis, which selectively kill caterpillars that eat sprayed leaves.
Hope that helps!
Yours,
Sounds like you are growing interesting plants and have this pest caterpillar. Unfortunately, there are so many types of caterpillars that unless it is really distinctive or is on a plant I am really familiar with, I have a hard time to ID them from photos. If I have specimens to look at under my dissecting microscope, I can key them to family. Otherwise, the best way to determine the species is to rear a few specimens to adulthood, and the adults are much easier to ID to species.
That being said, I can tell that the caterpillar you found is not the green cloverworm (Hypena scabra). I can tell that by looking at the prolegs (fleshy leg-like structures on the abdomen). The majority of caterpillars, including the one you found, have 5 pairs of prolegs (4 pairs on the middle abdominal segments and one pair on the last abdominal segment). In contrast, the green cloverworm is one of the species with only 4 pairs of prolegs (3 pairs on the middle abdominal segments and one pair on the last abdominal segment).
If you continue to see more of these caterpillars feeding on your Persicaria tinctoria, you could pick them off and freeze or squish them to kill them. If there are too many to keep up with, you might want to try a spray containing Bacillus thuringiensis, which selectively kill caterpillars that eat sprayed leaves.
Hope that helps!
Yours,
