What a difference 20 degrees makes! Trap catches in the Vegetable IPM Program blacklights have been very light over the past week. When night-time temperatures drop below 60 degrees F, insect activity subsides. Contributing to the reduction of insects in the traps is the end of the first generation flight of European corn borer moths and something of a break in the early season flight of corn earworm.
However, in the past two days night-time as well as day-time temperatures have risen and suddenly our traps are filling with insects. The majority of these are beetles – large numbers of scarab beetles – that are normally abundant at this time of year. Several species of these beetles feed on plant foliage and many species are nocturnal feeders so that feeding damage appears overnight. Backyard gardens as well as commercial plantings are susceptible to these pests.
Some of the more common beetle species that are now out are various June beetles, chafers, Asiatic garden beetle, carrot beetle, Japanese beetle and false Japanese beetle. These beetles feed on plants sometimes causing significant damage to vegetable crops and ornamentals. Their damage appears as ragged holes usually on leaf margins, but sometimes within the leaf.
The oriental beetle is also abundant. Its a pest of root crops but larvae also feed on the roots of sod, blueberries, ornamentals and row crops like field corn. The larvae feed on the roots but the adults either don’t feed or feed very little on foliage.
The sudden change in temperature has helped bring out our native brown stinkbugs, the Euschistus species. These are normally pests of fruiting vegetables but they are just now beginning to make their appearance in the adult stage. There has been some interest in whether the brown marmorated stinkbug would outcompete the native stinkbugs.