Plant and Insect Diagnostic Clinic Update - August 12, 2009

The following are highlights and updates about samples and questions received in the Clinic during the past two weeks:


Sap Beetles are even more common now than when mentioned in the previous issue of HHPN.  Several gardeners and growers have called to complain about damage to melons, tomatoes and sweet corn.  See Horticulture and Home Pest News, July 25, 2007.

Wasps are at their end-of-the-summer peak and people are noticing activity  by yellowjacket wasps nesting under the porch steps or in the foundation and cicada killer wasps burrowing at the edge of the flower bed.  The number of phone calls and emails about cicada killer wasps is much lower than in the recent past, which corresponds to our neighborhood observation that populations are down, which is a great relief to people we meet.

Wasps are ecologically beneficial insects that seek caterpillars and other insects to feed to their young. If a nest is located where it is out of the way and not likely to be disturbed, it is best left alone. If, however, a nest is located in a "high traffic" area such as along walks or near doorways, control is justified to reduce the threat of being stung.

Nests outdoors in walls or in the ground can be destroyed by placing an insecticide dust in the nest entrance during the night. The dust particles will adhere to the insects as they leave and reenter the nest and control will usually be achieved within a few days. Do not plug a nest opening in a house wall until you are sure all activity within the nest has stopped.

Above ground nests on trees and houses can be treated with aerosol sprays specifically made for this purpose labeled for use against wasps outdoors. These spray cans shoot the insecticide several feet. Treat nests at night when all of the workers are at the nest and the chances of being stung are lower. Retreat in 2 or 3 days if necessary.


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