David Owens, Extension Entomologist, owensd@udel.edu
Cucurbits
Continue scouting for spider mites. Focus on the crown area and especially around non-crop habitat. For other cucurbits, squash bug and squash vine borer are both active. Squash bug control is often a 2-spray deal, the first to get the adults and nymphs and the second to remove nymphs as they hatch from those eggs.
Peppers and Beets
We have just started catching small numbers of beet armyworm in western Laurel. Scout for defoliation in beets and peppers. Beet armyworm lay egg masses and early instars will attach leaves together with silk and feed and as a group in the silk webbing. Beet armyworms are green and have a small black spot above the second pair of legs behind the head. It is important to identify them from other caterpillars because they are resistant to pyrethroid insecticides.
Sweet Corn
We have begun vial bioassays as part of a USDA-NIFA-SCRI 2023-51181-41157 grant. Moths are being tested against 5 ug of cypermethrin, bifenthrin, lambda cyhalothrin, and beta cyfluthrin. Cypermethrin has long been the standard, and so far, 9.5% of cypermethrin treated moths have survived, which is a little greater than in years past at this time. Beta cyfluthrin has only had 1.9% moth survivorship, while bifenthrin has so far had 15.9% and lambda cyhalothrin with 18% survivorship.
Moth counts are coming down. Tuesday trap counts and UD thresholds can be found here: https://www.udel.edu/academics/colleges/canr/cooperative-extension/sustainable-production/pest-management/insect-trapping/. Thursday trap counts are below:
| Location | Blacklight Trap | Pheromone Trap |
| Dover | 1 | 36 |
| Harrington | 0 | 51 |
| Milford | 1 | 12 |
| Rising Sun | 0 | 6 |
| Wyoming | 0 | 57 |
| Bridgeville | 0 | 6 |
| Concord | 0 | 6 |
| Georgetown | 1 | 3 |
| Greenwood | 0 | 12 |
| Laurel | 1 | 32 |
| Lewes | — | 9 |
| Milton | — | 15 |
| Whaleyville | — | 31 |