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SCOLIID WASPS

R. L. Brandenburg & J. R. Baker, Extension Entomologists

CAUTION This information was developed for North Carolina and may not apply to other areas.

[General Information] [Biology] [Control] [Other Resources

SCOLIID WASPS, HYMENOPTERA: Scoliidae

wasp with band and dotsScoliid wasps are dark in color, often metalic, relatively large, robust, slightly hairy insects with light yellow spots or other markings. One of the most common Scoliid wasps in North Carolina is Scolia dubia. It is sometimes referred to as the blue-winged wasp. The adult is over one-half inch long with black antennae and a shiny black head, thorax and fore abdomen. About midway along the abdomen are two yellow spots (one on each side). These may appear as a band across the abdomen when the wasp is flying. The latter portion of the abdomen is brownish and somewhat fuzzy. The wings are dark blue.

Biology

Scoliid wasps are usually considered beneficial insects because they help control green June beetle and other grubs. Scoliid wasps are present in North Carolina from June to October.  However, they are most abundant during August. The female wasp flies low across the soil in search of grubs. When it detects one, it digs through the soil burrowing its own tunnel or following one made by the grub. Once locating a grub, she stings it on the throat and paralyzes it. The grub at first appears to be dead but after a day or so it can feebly move its legs. Such paralyzed grubs can live for a considerable time. The female wasp then lays an egg transversely on the third segment of the grub. The paralyzed grub provides a fresh food supply for the wasp larva after it hatches from the egg. Once a grub has been stung, it never recovers.

scolia dubia hovering over lawnThese wasps, therefore, are very important natural agents in the control of green June beetle grubs in the soil. Adult Scoliid wasps feed on nectar and pollen of flowers. They will not sting unless greatly aggravated or captured in the hands. In early August, the wasps often rest on plants but later they burrow into the soil to spend the night. Scoliid wasps are often noticed flying just a few inches above lawns infested with grubs in a loose figure-eight pattern. Sometimes these wasps are quite abundant and conspicuous as they fly their mating dances. After mating, females spend more time digging for grubs and flying wasps are not as noticeable.

Control

Since there is no record of anyone having been stung by Scoliid wasps, no control measures seem needed. Their presence, however, means that grubs are present.  A little monitoring for an infestation may be appropriate. If grubs have been a problem, see Ornamentals and Turf Insect Note No. 67, White Grubs in Turf.
Recommendations of specific chemicals are based upon information on the manufacturer's label and performance in a limited number of trials. Because environmental conditions and methods of application by growers may vary widely, performance of the chemical will not always conform to the safety and pest control standards indicated by experimental data.

Recommendations for the use of chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by the North Carolina Cooperative Extension Service nor discrimination against similar products or services not mentioned. Individuals who use chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage and examine a current product label before applying any chemical.

For assistance, contact your county North Carolina Cooperative Extension Service agent. .

Other Resources


Published by North Carolina Cooperative Extension Service

Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age, or disability. North Carolina State University at Raleigh, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.
© 2001 NC Cooperative Extension Service

Prepared by: R. L. Brandenburg & J. R. Baker, Extension Entomologists
Photos by J.R. Baker and Mike Wilder
ENT/ort-12 June 1994 (Revised April 2000)

Web page last reviewed January, 2010 by the webperson.