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Wasps and Bees in the Landscape

August 12, 1998

Several types of wasps and bees are frequently encountered nesting in turf areas, trees, and shrubs. All but the honeybee nest for only one year, starting new nests each spring. Professional landscapers must frequently control these insects in order to perform plant maintenance at a site. Bees and wasps will likely attack if you are within three feet of their nest opening. Take precautions when working around stinging insects. A protective bee suit is always a good idea--or at least wear a bee veil to keep attacking insects away from your face. Close collars tightly and fasten pant and shirt cuffs with rubber bands to keep the insects from getting underneath clothing.

Wasps and bees are day-active insects, so use nest control measures in the evening. This makes it less likely that returning foraging individuals will attack from behind while you are attacking the nest. Disturbed wasps and bees will fly toward a light, so work around nests when there is still enough light to see without a flashlight. If you must use a flashlight, cover the lens with red plastic or cellophane. Wasps and bees can't see red.

Underground nests are best controlled by flooding the nest with diazinon, mixed as directed. For quick application, pouring the insecticide out of a bucket may be effective. Immediately after the application, throw a shovelful of soil down the nest opening or stuff a rag into the opening and soak it with the insecticide. This makes it more likely that wasps and bees boiling out of the hole are slowed down enough to be killed by the insecticide. Needless to say, don't hang around. Get out of the area and return in the morning to check on the effectiveness of control. Solitary nesting wasps such as cicada killers can be controlled by spraying the ground in the nesting area with diazinon during the day or evening.

Entrances above ground can be lightly dusted with carbaryl (Sevin) dust. The insecticide should not clog the hole that the insects enter. Instead, cover surrounding surfaces so that insects walking into the holes get the dust on their feet and bodies. They will groom themselves and feed each other in the nest, which will kill off the nest in about five days. If honeybees are treated, close off the hole as soon as the nest is dead to prevent bees from other colonies from entering to steal the unguarded honey. Such honey can cause the death of beekeepers' colonies in the area.

Author: Phil Nixon


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