Notes on Blueberry Insects
Blueberry maggot is a regulated pest. The federal Plant Protection Act
and Regulations place movement restrictions on blueberry fruit, plants,
soil and containers from areas known to be infested with blueberry maggot.
These laws exist to prevent the spread of this pest from infested areas,
such as Nova Scotia, New Brunswick, Prince Edward Island, Maine, New York,
Michigan, to non-infested areas, such as Ontario, Quebec and B.C. All
infestations of blueberry maggot must be reported to the Canadian Food
The adult blueberry maggot is a fly that is slightly smaller than a housefly.
It has a grey-black body with a white spot and distinct dark banding on
its wings (see Figure 1). Wing patterns of apple maggot and other related
species. The immature stage is a white larva that infests blueberry fruit
(See Table 1).
Wing patterns of apple maggot and other related species
Table 1: Distinguishing Insect Larvae Found in Blueberry
||Brown head capsule
||Brown head capsule
||Has 3 pairs legs plus prolegs
||No head capsule
Period of activity
In early July, as the first berries are turning blue, adult flies begin
to emerge from pupae in the soil. Emergence and adult activity continues
into August. Adult flies lay eggs on developing blueberry fruit and larvae
develop inside the fruit. Infested fruit may ripen and soften prematurely.
Mature larvae emerge from dropped fruit, then pupate and overwinter in
the soil beneath the bushes.
Monitoring and thresholds
Monitor for blueberry maggot flies using yellow sticky traps baited with
ammonium acetate. These traps are also used for apple maggot. Place traps
in the top 1/3 of the bush, by mid-June, on the perimeter of commercial
fields. If abandoned or wild blueberries are nearby, place traps just
outside of commercial fields. Clear plant foliage away from the trap so
it is plainly visible. See Pest Monitoring Equipment Suppliers on the
Insecticides and timings for blueberry maggot control are listed in the
OMAFRA Publication 360 Blueberry Calendar..
- The township of Wainfleet in Niagara region, the township of Charlotteville
in Norfolk and specific sites in Brant and Elgin counties have restricted
areas with quarantines in place to eradicate blueberry maggot and to
prevent its spread.
- In restricted areas, begin sprays for blueberry maggot when berries
begin to turn blue or when the first maggot flies are detected on traps.
In other areas, spray the border of the planting (outer six to eight
rows of blueberries) to reduce the risk of infestation.
- Monitor new plantings closely for blueberry maggot, especially if
planting stock originated in an infested area.
- Do not use Cygon or Lagon on blueberries destined for markets in the
United States because there is zero tolerance for the active ingredient
dimethoate on blueberry fruit in the USA.
- If blueberries are bought for re-sale on your farm, do not throw away
the culls and unmarketable berries. Deep burial, below the plough layer,
is the best way to dispose of this material.