Dasineura piceae (Formerly Mayetiola piceae)

Spruce gall midge damage on white spruce. Note the previous seasons damage - open galls - and the current seasons damage - swollen stems. Photo: Bruce Watt, University of Maine, Bugwood.
Scientific Name: Dasineura piceae (Formerly Mayetiola piceae)
Common Name: Spruce Gall Midge
Growing Degree Days (GDD's): None available at this time.
Host Plant(s) Common Name (Scientific Name)
Black hills spruce (Picea glauca)
Norway spruce (Picea abies)
White spruce (Picea glauca)
Insect Description:

The spruce gall midge is a tiny species of fly which overwinters in a gall that looks like numerous swellings that circle terminal shoots. As the flies develop within the galls, they push against the tips of the end of the swellings as they pupate, and eventually emerge as adults. Midges emerge from galls in late May to early June. The adult flies mate and females lay eggs on newly developing host plant buds. Tiny, bright orange larvae hatch from the eggs within a couple of weeks and bore into the host plant shoots where they feed on plant fluids. The plant's response to this feeding is for the tissue to swell around the larvae and form galls. The larvae continue to feed within the galls throughout the growing season. Greater detail about the life cycle and seasonal timing of the spruce gall midge is lacking.
Damage to Host:

The spruce gall midge feeds on the foliage of Norway and white spruces. Injury caused by this insect may be confused with that of the eastern spruce gall adelgid. Individual shoots may be killed by the activity of this insect. Repeated injury by the spruce gall midge may cause brooming (disfigured, prolific shoots at the end of the twig). Entire trees are rarely covered in the galls created by this insect. As such, damage may be primarily aesthetic and easily managed with cultural/mechanical management options.
Monitoring:

Trees can be visually inspected early in the spring to look for the presence of the galls. 
Cultural Management:

If galls are found before the insects have emerged, they can be pruned from the host plant and destroyed. This may lower the population of spruce gall midge on a single tree or ornamental planting. 
Natural Enemies & Biological Control:

None noted at this time.
Chemical Management:

Acephate (NL)

Azadirachtin (NL)

Carbaryl (L)

Cyfluthrin (NL)

Deltamethrin (L)

Flonicamid+cyclaniliprole (N)

Gamma-cyhalothrin (L)

Imidacloprid (L)

Lambda-cyhalothrin (L)

Spinosad (NL)

Thiamethoxam (N)
Notes:

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

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".