and life cycle—Apple maggot
Apple maggots overwinter as pupae in the soil. Generally there is one generation a year, although there
may be a partial second generation in warm years. Adults emerge in mid-June to early July; emergence usually
peaks between mid- and late July and is over by late August. In some places, some of the pupae may remain
in the soil and will not emerge until the following year.
When flies emerge in summer, they are sexually immature
and must feed on honeydew produced by aphids, psyllids,
and scales before they are ready to mate. Female flies lay
eggs singly under the skin of apples and then mark the apple
with a pheromone to keep other females from laying eggs.
Females lay about 300 eggs over a 30-day life span. Eggs
hatch in 2to 10 days, depending on temperature. Larvae are
cream colored with a blunt posterior and a tapered front
end that contains two black mouth hooks. They feed within
the apple and pass through three instars before completing
developing in 20 - 30 days. Infested fruit fall to the ground;
larvae leave the fruit, burrow into the soil, and molt into
a fourth instar and then into a pupal stage to overwinter.
larvae tunneled into apple flesh