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.
SCOLIID WASPS, HYMENOPTERA: Scoliidae
Scoliid
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 digs through the soil in search of grubs, burrowing her own tunnels
or following those made by grubs. 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.
These 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.
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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, 2008 by the webperson.