Resseliella liriodendri

Tuliptree spot gall midge leaf galls. Photo: Lance S. Risley, William Paterson University, Bugwood.
Scientific Name: Resseliella liriodendri
Common Name: Tuliptree Spot Gall (Midge)
Growing Degree Days (GDD's): None available at this time.
Host Plant(s) Common Name (Scientific Name)
Tuliptree (Liriodendron tulipifera)
Insect Description:

The tuliptree spot gall midge causes the formation of eyespots on the leaves of tuliptree. The very center of the spot forms a dense, rounded gall. This damage can often be mistaken for fungal activity. As the host plant leaf ages and dries, dead tissue can drop from the leaf, leaving behind a perfectly round hole. These eyespots are 0.16 - 0.28 inches in diameter. This midge is known to have several generations per year, with larvae dropping to the soil or leaf litter to pupate after emerging from a slit in the leaf, once fully mature. Like other eyespot gall makers on different hosts (such as red maple), very little is known about the specifics of the insect's biology and life cycle.
Damage to Host:

Foliage of tuliptree is impacted. An eye-spot gall with appearance similar to fungal leaf spots is created by this insect. The galls are sometimes described as purplish leaf blisters (Felt, 1940). Forest stand trees may host higher populations of this insect, however further long term investigation is necessary. In a 1989 study in Georgia, forest stand trees had higher levels of herbivory from the tuliptree spot gall midge than those grown under open field conditions (Dudt and Shure, 1994). The tuliptree spot gall midge very rarely requires chemical management intervention. Chemical management options for this insect are rarely, if ever, recommended. 
Monitoring:

Eyespots on tuliptree created by the tuliptree spot gall midge may be seen during the summer months on host plant foliage. As the galls and leaf tissue dries out, round holes may drop from the leaves. Do not confuse for fungal activity.
Cultural Management:

If the insect is pupating in the leaf litter nearby suitable host plants, presumably sanitation and raking the leaf litter and disposing away from ornamental trees could potentially reduce a single-tree population of this insect. However, damage to the host plant leaves is typically not considerable for overall tree health, and can be tolerated.
Natural Enemies & Biological Control:

Very little is known about the natural enemies of the tuliptree spot gall midge at this time.
Chemical Management:

Acephate (NL)

Azadirachtin (NL)

Carbaryl (L)

Cyfluthrin (NL)

Deltamethrin (L)

Flonicamid+cyclaniliprole (N)

Gamma-cyhalothrin (L)

Lambda-cyhalothrin (L)

Spinosad (NL)
Notes:

Applications, if necessary, may be made in the spring before adults finish laying eggs; must be made prior to leaf spot formation to be effective. However, chemical management options for the tuliptree spot gall midge are rarely, if ever, necessary.

Active ingredients that may be applied systemically include: azadirachtin (injection, soil drench) and acephate (injection).

Make insecticide applications after bloom to protect pollinators. Applications at times of the day and temperatures when pollinators are less likely to be active can also reduce the risk of impacting their populations.

Note: Beginning July 1, 2022, neonicotinoid insecticides are classified as state restricted use for use on tree and shrub insect pests in Massachusetts. For more information, visit the MA Department of Agricultural Resources Pesticide Program.

Read and follow all label instructions for safety and proper use. If this guide contradicts language on the label, follow the most up-to-date instructions on the product label. Always confirm that the site you wish to treat and the pest you wish to manage are on the label before using any pesticide. Read the full disclaimer. Active ingredients labeled "L" indicate some products containing the active ingredient are labeled for landscape uses on trees or shrubs. Active ingredients labeled "N" indicate some products containing the active ingredient are labeled for use in nurseries. Always confirm allowable uses on product labels. This active ingredient list is based on what was registered for use in Massachusetts at the time of publication. This information changes rapidly and may not be up to date. If you are viewing this information from another state, check with your local Extension Service and State Pesticide Program for local uses and regulations. Active ingredient lists were last updated: September 27, 2024. To check current product registrations in Massachusetts, please visit the MA Department of Agricultural Resources Pesticide Product Registration page and click on "Search Pesticide Products Registered in Massachusetts - Kelly Solutions".