The Blueberry fruit fly, Rhagoletis mendax Curran has been found in all Atlantic Provinces and in the Eastern US. While the larvae damage the fruit, most of the damage comes from the presence of larvae in the harvested fruits. The female fly lays an egg under the skin of the berry and the developing larva feeds on the pulp of the berry, therefore causing it to become shriveled and the infested berry tends to drop off the plant prematurely. Although the larva is not harmful to human health, its presence in the harvested fruit however makes fresh, canned or frozen fruit unacceptable for sale.
The blueberry fruit fly also attacks other types of berries that are found together with blueberries like huckleberry, shadbush (serviceberry), barrenberry, bunchberry, wintergreen, lingonberry.
The four life stages of the blueberry fruit fly are: egg, larva (maggot), pupa, adult fly. Starting mainly in late June – early July the emergence of the adult fly varies on the location and the year. Almost all the flies emerge over a period of thirty days. After a one to two week development the adult females begin the egg-laying, which will last for fifteen to twenty-five days.
However, the egg laying continues for thirty days since the adult flies emerge over an extended period of time and there is usually one egg per berry. The white, hatched larva feeds for two to three weeks and is 8 mm long when fully-grown. The insect overwinters as a pupa in the soil (3-5 cm below the surface) after they leave the berry in mid to late-August.
The Canadian Food Inspection Agency regulates the movement of wild (lowbush) blueberries within Canada in order to prevent the introduction and/or spread of this pest. Regulations regarding the importation of wild blueberries from the continental United States and other countries that are infested with the blueberry fruit fly are also in place.