I’ve consistently seen flea beetle damage on young cotton this season. Small feeding marks on the cotyledon leaves—especially in fields planted with untreated seed—are a sign of flea beetle activity. I’m mostly seeing pale-striped flea beetles. These insects have chewing mouthparts that scrape both the upper (more common) and lower surfaces of the leaves. At first, this doesn’t create visible holes, but as the damage ages, it turns into obvious holes in the cotyledons.
Flea beetle damage usually stays limited to cotyledon leaves
and is mostly cosmetic. I haven’t seen much injury to seedlings in fields
planted with neonicotinoid-treated seeds. Flea beetle infestations tend to be
patchy and are more common along field borders, edges, and near drying weedy
areas. Treatment is rarely needed and should only be considered if they begin
to threaten stand establishment—which is very uncommon with flea beetles.
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| Striped flea beetle on cotyledon leaf |
Another insect I’ve been spotting across several fields in
the South Plains is the darkling beetle from the genus Blapstinus. These
beetles are about ¼ inch long and black. Their larvae, known as false
wireworms, feed on the underground parts of young seedlings. While only the
larvae cause wireworm or false wireworm damage, the adult Blapstinus
beetles are also known to feed on plants. You can often find several beetles
clustered at the base of a single plant. Their chewing damage shows up on the
stems, right at or just below the soil surface. If you see stand-threatening
damage along with a heavy presence of these beetles, I recommend applying a foliar
spray with a pyrethroid insecticide.
