Blueberry maggot
Rhagoletis mendax
| Type | Insect |
|---|---|
| Pressure by region | High pressure: Northeast |
About
A small black fruit fly with zigzag black bands on its wings and a white dot on its back, a close cousin of the apple maggot. Its white, legless maggots live inside ripe blueberries.
Spotting it
Damage
Maggots eat the pulp and can destroy the whole berry. Females lay only one egg per berry, but unsprayed plantings can lose the whole crop (UNH).
How to find it early
Yellow sticky boards baited with ammonium carbonate, or red spheres, show when flies arrive. Squeeze or cut open soft berries and look for maggots.
When
Early to late summer; in New Hampshire adults emerge around June 30 and peak in the first half of July.
Life cycle
Maggots drop to the soil and spend winter there as pupae; some stay in the ground up to five years before emerging (UF/IFAS). There is one generation a year, with adults emerging about the time the first berries ripen.
What to do, gentlest first
Start at the top. Sprays are a last step; always read and follow the product label.
Pick often and clean up Prevent
Harvest ripe berries frequently so flies have fewer to lay eggs in (UNH), and remove dropped and overripe berries.
Monitoring traps Trap
Hang yellow sticky boards baited with ammonium carbonate (UF/IFAS) or red spheres as berries begin to color, so you know when flies are active.
Traps show timing; they do not control the fly.
Insecticides timed by trap catches Conventional spray
UNH notes both organic and conventional insecticides registered for this pest. UF/IFAS advises a short-residual product during harvest, applied only when traps show flies.
Many insecticides are toxic to bees (PNW 591); do not spray while bushes are in bloom. Check that blueberry is on the label and follow its pre-harvest interval.
Plants it goes after
Pressure by region
UF/IFAS lists it from New England south to Florida and Alabama, and in Michigan and Tennessee; it has been in the Southeast only since 1991 (Georgia). California regulates fruit from eastern states to keep it out. No source says it is present in the West, so the western, Alaska and Hawaii ratings, and the South Central and Great Plains ratings, are estimates; it may well be absent there.
| Northeast | High pressure |
|---|---|
| Southeast | Moderate |
| South Central | Low |
| Midwest | Moderate |
| Great Plains | Low |
| Mountain West | Low |
| Southwest | Low |
| Pacific Northwest | Low |
| California | Low |
| Alaska | Low |
| Hawaii | Low |
Ratings come from extension sources where available; some are estimates, as noted above.
Sources
Planting dates and advice are general guidance; check with your local Cooperative Extension office for your area.