Pest description and damage The honeylocust pod gall midge is a tiny orange gnat. The small bright pink maggots feed within the galls which are leaves that have become deformed, thickened, and podlike. The larvae are sheltered inside the deformed leaves. Infested leaves may dry and drop from the tree. Small shoots may be killed. Although trees are unlikely to be killed, the ornamental quality of the tree may be lost. Thornless varieties of honeylocust are especially subject to damage. Damage from this gall maker is most noticeable in nurseries, but less objectionable in landscapes, especially if the tree is viewed from a distance.
Biology and life history The midge overwinters as pupae in cocoons in the upper 2 inches of soil near the base of the tree trunks (generally within 1 foot of the trunk). The adults emerge and form small swarms around the tips of leaves, as the trees are just beginning to leaf out. Adult midges deposit eggs on new foliage along the rachis or on the edges of developing leaf buds. The first pod gall midge eggs generally are found during the last week of March through the first week of April. The eggs usually hatch in 2 days. The young larvae crawl along the leaf and begin feeding. Only one larva is required to initiate galling of the leaf. Soon after this initial generation, the populations appear continuous with many life stages present. There are multiple generations each year, as little as 3 to 4 weeks apart.
Prune out infested growths.
Management-chemical control: HOME USE
The key to successful management is to protect new foliage with insecticide. Sometimes repeat applications are needed, at 2 to 4 weeks, beginning in late spring.
Management-chemical control: COMMERCIAL USE
The key to successful management is to protect new foliage with insecticide. Sometimes repeat applications are needed, at 2 to 4 weeks, beginning late spring.
- horticultural oil (late March or early April)-Some formulations are OMRI-listed for organic use.
- spinosad A&D-Some formulations are OMRI-listed for organic use.
For more management options
See "Gallmakers" in:
For more information
Rosetta, R., N.C. Bell, and T.L. Collins. Monitoring and Control of Honeylocust Pod Gall Midge (http://oregonstate.edu/dept/nurspest/Honey_Locust%20_Pod%20_Gall%20_Midg...)