Cicada killers, mistaken for hornets, are beneficial bugs

Published 12:00 am Friday, August 8, 2008

By Darrell Blackwelder
For the Salisbury Post
Cicada-killers are giant hornet-like insects that are actively terrorizing homeowners throughout Rowan County.
Many have called concerned about these giant “hornets” buzzing them and digging up their lawns and shrub beds. It’s understandable that homeowners would think that these large wasps are an imminent threat, especially to those allergic to bee stings or with small children.
However, these large, slow flying wasps do not aggressively sting like yellow jackets, hornets or wasps. Ironically they tend to be somewhat curious, buzzing people as they walk through their lawns and gardens. No one has ever complained to me of being stung by a cicada killer.
Late summer is when cicada-killers in our area are most active. They have emerged and are actively seeking cicadas for their young. Unfortunately, they aggressively seek cicadas, burrowing into lawns and shrub beds.
Male wasps live for about two weeks, patrolling their territory and fighting with other males. Females live about four weeks, working hard, digging burrows and hunting food for their offspring. Researchers have calculated that in a typical season, 100 female cicada-killers can eliminate more than16,000 cicadas from the surrounding area.
Cicada-killer females paralyze cicadas with their stinger and feed to their young. Cicada-killer grubs hatch from the egg in a few days, feed on the cicada and over-winter underground in a hard cocoon. The insect hatches in early to mid-July and digs its way to the surface.
Cicada-killers can be controlled with Sevin dust or other pesticides near the nests’ entrance. Be careful not to disturb the burrow as the female must walk through the dust for control. You may need to repeat treatments for 2-3 weeks if new wasps move into the area.
At close range, adults can be killed with a wasp aerosol as they light on foliage or enter the nest burrow. If you do not feel comfortable treating the area, contact a licensed pest control operator. Always read the label directions to confirm current listing of pests, and follow safety precautions, before using any insecticide.
Please note: Spraying the burrows only kills the female and not all her offspring since they are walled off in chambers underground.
Another way to prevent cicada-killer nesting is to plant dense, tall vegetation or mow your lawn at the highest setting during the nesting season.
In shrub and flower beds, make sure you have a three-inch layer of mulch. The wasps don’t live very long, so at most they will be a pest about two months out of the year.
Even though their look is menacing and they do cause some minor damage to the landscape, these insects do feed on other insects and should be considered one of few “good” wasps.
Darrell Blackwelder is an agricultural agent in charge of horticulture with the North Carolina Cooperative Extension Service in Rowan County; 704-216-8970.
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