Publication E-39
September 1966
Purdue University
Cooperative Extension Department
Department of Entomology
PICNIC BEETLES
Picnic beetles are outdoor scavengers that feed primarily on overripe or damaged fruits and vegetables, and to some extent on decayed portions of bulbs and roots. However, they are better known as those persistent, black, hard-shelled intruders that swarm around a picnic or barbecue and drop lazily into both food and drink or otherwise make themselves a nuisance.
The beetles are about 3/16 to 1/4 inch long and jet black with four pale yellow spots on their wing covers . They are difficult to control for even if killed in large numbers, more are likely to come in from untreated areas.
PREVENTION
Since picnic beetles are scavengers, anything that can be done to prevent or eliminate overripe, insect- or diseased-damaged fruits and vegetables will be helpful. Apples, mulberries and other fruits that fall to the ground and decay should be either picked up and destroyed or sprayed with 1% dichlorvos (DDVP). Likewise, keep melon rinds and other garbage in tight containers.
CONTROL AROUND OUTDOOR EATING AREAS
Reasonably good control in outdoor eating areas can be obtained by (1) spraying the area with a residual insecticide, (2) applying a space spray just before eating, and (3) using a bait to attract the insects away from the area.
Residual insecticides that can be safely applied to grass and most vegetation around eating areas are malathion 57% EC., diazinon 25% EC., carbaryl (Sevin) 80% powder. Select one and use it at the rate of 2 tablespoons of material to each 3 gallons of water.
Space sprays or mists containing pyre-thrins and/or dichlorvos (DDVP) are available in aerosol containers. They give quick knock down and kill of insects present and should be used just prior to putting food on the tables.
One of the most effective ways of handling backyard picnic beetle problems is to bait the area before using it. First, place material like melon rinds or cut tomatoes in pans and spray with 1% dichlorvos (DDVP). Then, 1 or 2 hours before eating, place the bait pans in a circle about 20 feet from the area. Use at least 4 bait pans. Most of the beetles in the area will be attracted and killed before they can be a nuisance.
PROTECTING RIPENING FRUITS AND VEGETABLES
Picnic beetles readily attack overripe or injured strawberries, raspberries and other small fruits. They also feed on injured tomatoes and ears of corn damaged by the earworm or corn borer. These crops can be somewhat protected by repeated sprayings with malathion 57% EC or carbaryl (Sevin) 80% powder at the rate of 2 tablespoons per 3 gallons of water. These materials can be used on most fruits and vegetables within a few days of harvest, but check the label first and observe harvest restrictions.