Blueberry Maggot – Rhagoletis mendax

Blueberry Maggot: Appearance, Territory, Damage and Life Cycle Latin Name: Rhagoletis Mendax Appearance: The mature blueberry maggot is about 3/16 of an inch long and looks like a little housefly with black bands on its wings. Larvae (or maggots) are legless and can reach a length of 5/16 inch. At the mouth end of each larva is a single hook-like teeth. Blueberry maggots resemble the closely related apple maggot in appearance, with adults being almost identical in size and appearance (including wing patterns). Apple maggot, on the other hand, does not eat blueberries. Host Plant: The only commercially cultivated fruit crop impacted by blueberry maggot is blueberry both high bush (Vaccinium corymbosum) and low bush (V. angustifolium, V. myrtilloides and V. vacillans). Plants of the genera Vaccinium and Gaylussacia, such as wild blueberries, lingonberries, dangleberries, dewberries, and huckleberries, are natural hosts. Territory: The blueberry maggot was first discovered in Wisconsin in Adams and Sauk Counties in the summer of 2016. This insect feeds on the insides of blueberries, causing harm to commercial blueberry production in the eastern and southern United States, as well as eastern Canada. This bug is likely to have a considerable influence on Wisconsin blueberry output in the future. Damage Caused: Each fruit is fed by a single larva, which causes the berry to soften as it grows. Damage may go undiscovered until after harvest, when maggots emerge from the fruit and appear among fresh blueberries or processed blueberry products (e.g., jams, preserves, pie fillings). Life Cycle and habits: The blueberry maggot, or blueberry fruit fly, is the major insect pest of blueberries in Maine. The first flies begin to emerge from the soil in late June or early July. The date of initial fly emergence is dependent upon soil temperature. Emergence will begin to take place in mid-June if spring temperatures have been very hot, but not until mid-July if spring temperatures have been unusually cool. Flies continue to emerge until early August. After emerging, the flies, which live for about 30 days, and spend one to two weeks feeding on dew, insect honeydew, and secretions on foliage. Mating occurs on the fruit after which mated females seek out ripe blueberries in which to lay eggs. The females only lay a single egg in each fruit and each female can lay up to 100 eggs (infesting up to 100 fruit) in a period of 15 to 25 days. The female fly punctures the skin of the blueberry with a long-pointed structure called an ovipositor which can be withdrawn into the insect’s abdomen. The fly then drags the ovipositor over the surface of the berry leaving behind a chemical called an ovipositing deterring pheromone. This chemical deters other flies from laying an egg in the same berry for a few days. In seven to ten days the egg hatches and the larva (maggot) begin feeding. After two or three weeks of feeding, the larva becomes full-grown, and the berry is almost completely destroyed. The larvae burrow into the soil to a depth of one to two inches to pupate. In the first year after pupation, approximately 85 percent of the adult insects emerge. In the second year, roughly 10 percent emerged. In the third and fourth years, the remaining 5 percent of the flies emerge. If a calamity should befall the population in any given year, some of the pupae would still be in the soil to emerge later.