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How to identify it
- The adult is a very small reddish fly, about 1 to 3 mm long.[1]
- The larvae are white to orange and so small that they are hard to see with the naked eye. They live inside flower buds or developing shoot tips.[1][5]
- Infested shoot tips are distorted. Because the growing tip is killed, the shoot often branches and takes on a witches'-broom look.[1]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Boron deficiency and normal black tip | Shoot-tip damage can be confused with boron deficiency or with the normal black-tip stage of blueberry shoot development.[1] |
| Cranberry tipworm | Midges on cranberry, called cranberry tipworm, carry the same scientific name, but they produce and respond to a different sex pheromone, and researchers concluded the cranberry and blueberry populations are two separate cryptic species.[6] |
Where it lives
It is a serious pest of rabbiteye blueberries in Florida, Georgia and Mississippi and is increasingly found in highbush blueberries in the Great Lakes region, including Wisconsin and Michigan, where a survey found it on 43 of 46 farms. In Maine it has been an emerging pest of wild blueberry since its discovery there in 2003, and it also occurs in Pacific Northwest blueberries.[2][4][1]
Biology and life cycle
It spends the winter as a pupa in the soil. In spring, females lay eggs in flower or leaf buds just after bud swell, when the bud scales begin to separate.[1]
The eggs hatch within a few days, and the larvae feed inside the bud for about a week before dropping to the soil to pupate. There may be up to four generations a year; in Maine wild blueberry fields it appears to have three generations during the prune year, and in Michigan, populations peak several times through July and August.[1][4][2]
In rabbiteye blueberries it mainly damages flower buds, but in northern highbush blueberries it damages only the vegetative shoots.[2]
Tiny parasitic wasps attack the larvae. On a minimally managed farm in north-central Florida, 25 to 40% of larvae were parasitized over three years; larvae deep in the center of a bud were less likely to be hit, and 37% had been parasitized more than once.[5]
Midges from cranberry and from highbush blueberry use different sex pheromones, and researchers concluded that the two populations are separate species that look alike.[6]
Damage and signs
- Larvae feeding in developing shoot tips cause distorted growth. Killing the tip releases apical dominance, so the shoot often branches into a witches'-broom shape.[1]
- In Florida, Georgia and Mississippi it is a serious pest of rabbiteye blueberries, where it attacks the flower buds. In the Pacific Northwest, bud damage at an economic level has not been seen.[2][1]
- In Michigan northern highbush, infestation had no significant effect on flower bud production overall, but shoots damaged in August set significantly fewer buds than those damaged in June or July.[3]
- In Maine wild blueberry, infested stems produced fewer flower-bud clusters and fewer viable flowers in four of seven trials, but in two trials infested stems had more flowers. Prune-year fields are more heavily infested than crop-year fields, and fields under high-input management had less infestation than low- or medium-input fields.[4]
Health risk
These sources treat it only as a pest of blueberry buds and shoots; none mentions any effect on people.[1][2][5]
Control
Biological control
Parasitic wasps commonly attack the larvae and may play an important role in regulating the midge, and the Florida researchers discuss pesticide use in light of conserving them.[5]
Pesticides
Insecticides are the main tool in Florida, but they work only partly, because the larvae are sheltered inside the buds for most of their lives.[5]
For home plantings the Pacific Northwest handbook lists carbaryl, horticultural oils and spinosad. Its commercial options include acetamiprid, cyantraniliprole and spirotetramat, with spinosad giving suppression only.[1]
Monitoring
In Michigan, emergence traps were the most useful way to detect the first midges in April, while checking shoot tips for damage and dissecting shoots revealed the later population peaks. Infested tips turned up throughout the bush, with early infestation heaviest near the base.[2]
For Maine wild blueberry, researchers developed a sampling plan and economic thresholds tied to expected yield and price.[4]
Common questions
- Why are my blueberry shoot tips distorted, with bushy side branches?
- Blueberry gall midge larvae feeding inside shoot tips cause distorted growth and branching that looks like a witches' broom. The same symptoms can come from boron deficiency or the normal black-tip stage, and the white to orange larvae are tiny; Michigan researchers found them by dissecting shoot tips.[1][2]
- Is the blueberry gall midge the same as the cranberry tipworm?
- Both go by the name Dasineura oxycoccana, but midges from cranberry and from blueberry use different sex pheromones, and researchers concluded they are two separate cryptic species.[6]
- Does blueberry gall midge reduce the crop?
- It depends on the planting. It is a serious bud pest of rabbiteye blueberries in the Southeast, but in Michigan northern highbush it did not reduce flower bud set overall, and in the Pacific Northwest economic bud damage has not been seen.[2][3][1]
Sources
- Pacific Northwest Pest Management Handbooks (Oregon State, Washington State and University of Idaho Extension), “Blueberry: Blueberry gall midge (Pacific Northwest Insect Management Handbook).” pnwhandbooks.org/insect/small-fruit/blueberry/blueberry-blueberry-gall-midge (accessed 2026-11-09)
- Environmental Entomology (via NCBI PubMed), “Distribution and phenology of Dasineura oxycoccana (Diptera: Cecidomyiidae) in Michigan blueberries (N. G. Hahn and R. Isaacs; Environmental Entomology 41(3): 455-462, 2012; abstract).” pubmed.ncbi.nlm.nih.gov/22732602/ (accessed 2026-11-09)
- Journal of Economic Entomology (via NCBI PubMed), “Assessing the economic importance of Dasineura oxycoccana (Diptera: Cecidomyiidae) in northern highbush blueberries (N. G. Hahn and R. Isaacs; Journal of Economic Entomology 108(4): 1910-1914, 2015; abstract).” pubmed.ncbi.nlm.nih.gov/26470334/ (accessed 2026-11-09)
- Journal of Economic Entomology (via NCBI PubMed), “The blueberry gall midge (Diptera: Cecidomyiidae): a recent pest of wild blueberry and its impact on potential yield (J. A. Collins and F. A. Drummond; Journal of Economic Entomology 112(3): 1151-1161, 2019; abstract).” pubmed.ncbi.nlm.nih.gov/30835789/ (accessed 2026-11-09)
- Environmental Entomology (via NCBI PubMed), “Parasitism of Dasineura oxycoccana (Diptera: Cecidomyiidae) in north central Florida (C. R. Roubos and O. E. Liburd; Environmental Entomology 42(3): 424-429, 2013; abstract).” pubmed.ncbi.nlm.nih.gov/23726050/ (accessed 2026-11-09)
- Journal of Chemical Ecology (via NCBI PubMed), “Populations of the gall midge Dasineura oxycoccana on cranberry and blueberry produce and respond to different sex pheromones (S. M. Fitzpatrick et al.; Journal of Chemical Ecology 39(1): 37-49, 2013; abstract).” pubmed.ncbi.nlm.nih.gov/23297107/ (accessed 2026-11-09)
- iNaturalist, “Dasineura oxycoccana taxon page (order and family).” www.inaturalist.org/taxa/714297 (accessed 2026-11-09)