Spurgia esulae 
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Common Name
Leafy spurge tip gall midge
Weed Impacted
This fly attacks leafy spurge. Larvae feed and form galls on young stem tips. Galling and feeding by the larvae act to suppress flowering and seed production. The stem tips ultimately die, and new shoots develop below the attacked areas. Those shoots are attacked, so that plants are weakened with each new generation of midges.
Insect Description/Field Identification
Adults are small, nondescript, gnat-like flies. The presence of S. esulae in the field can be indicated by small, round galls on the leaves around stem tips. Mature larvae are orange and are found within the galls.
Life Cycle
Flies typically complete two or more generations per year. Eggs are laid on both exposed and developing leaves of young stem tips. Larvae hatch within galls, and then move to the internal part of the tip to feed on developing leaves. Most generations pupate within the galls; the overwintering generation pupates in soil near the host plant.
Availability
Availability of this insect is currently VERY limited. To inquire about availability and to request this biocontrol agent, please download, complete and submit this form.
Comments
S. esulae is generally considered secondary to Aphthona spp. for biological control of leafy spurge. Once established, adults can be dispersed by wind over long distances. Established populations of the midge may be susceptible to attack by parasitoids of native gall midges.
Using the Agent: Integrated Weed Management (IWM)
Leafy spurge is highly toxic, extremely difficult to control with herbicides, and nearly impossible to control with physical/mechanical or other methods. Roots can grow 3 to 7 m (10 to over 20 ft) deep, and new plants can sprout from pieces of roots as small as 1.3 cm (1/2 in) long and 0.25 cm (approx 1/8 in) thick. Thus, successful control of leafy spurge is usually a long-term process, and biological control is an critical component of effective management.
However, biological control should only implemented where infestations of leafy spurge are large and immediate eradication is not the main objective. Smaller satellite infestations should be sprayed annually, without skipping a year until control is over 90%. Consult with your county weed office, Extension office or an IWM practitioner to determine which herbicide treatments are safe and appropriate.
Sheep and goats can feed safely on leafy spurge, and grazing by these animals can also help slow spread of the weed. Do NOT, however, allow cattle to feed on leafy spurge. Ingestion of the plant by cattle can cause animal illness or death.
Any management of leafy spurge should include intensive revegetation with native or other desirable plants, especially grasses. Revegetation promotes plant competition, which stresses weeds and allows for more effective treatment. For more information about revegetation and IWM, click here.
For more information about integrated management of leafy spurge, follow the highlighted links in the references below:
References
Coombs, E. M., J. K. Clark, G. L. Piper, and A. F. Cofrancesco, Jr. 2004. Biological Control of Invasive Plants in the United States. Western Society of Weed Science, Oregon State Univ. Press, Corvallis.
Lym, R. G., and C. G. Messersmith. 2006. Leafy Spurge Identification and Chemical Control. North Dakota State University Extension Bulletin W-765. URL http://www.ag.ndsu.edu/pubs/plantsci/weeds/w765w.htm
Lym, R. G., and R. K. Zollinger. 1995. Integrated Management of Leafy Spurge. North Dakota State University Extension Bulletin W-866. URL http://www.ag.ndsu.edu/pubs/plantsci/weeds/w866w.htm
Photo Credits
Spurgia esulae adult - USDA archive photo, USDA APHIS PPQ, bugwood.org http://www.insectimages.org/images/768x512/3970078.jpg
Spurgia esulae galls - L.L. Berry, bugwood.org http://www.insectimages.org/images/768x512/5358605.jpg
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