European apple sawfly injury

Market Diseases of Apples, Pears, and Quinces
European Apple Sawfly Injury

Hoplocampa testudinea Klug

The European apple sawfly is a serious pest in northern Europe. It was first reported in Long Island, New York, in 1939. Since then the apple sawfly has spread to the southeastern part of New York, the northern part of New Jersey as far south as New Brunswick, southern Connecticut, and throughout Massachusetts. The insect is most serious in home orchards, but it can cause losses in commercial plantings if a timely spray schedule is not followed.

Many varieties of apples are infested, but the insect shows preference in Connecticut for Wealthy, Dutchess, Gravenstein, Early McIntosh, and Golden Delicious.

Damaged fruits are rarely seen on the market.

The symptoms of apple-sawfly injury at harvest are the results of healed tissues that were injured by the superficial feeding of larvae on very young apples. The healed areas appear as fairly broad streaks on the surface of the apple with a moderately brown, corky, checked surface. The corky streaks may be 1/4 inch or more in diameter at the broadest end and usually taper toward the other end. They are slightly sunken but do not extend into the flesh and are inclined to be somewhat curved (see photo). The symptoms are striking and different from other insect injuries on apples.

The apple sawfly overwinters in the soil as mature larvae. Adults emerge when apples are in bloom. Egg laying occurs during full bloom of the apple trees, and the eggs are inserted in the calyx cup. Newly hatched larvae tunnel under the surface of the skin of very young apples. An individual larva may feed near the surface of several apples before it bores to the center of the young fruit. Badly damaged fruits with larvae in the core area drop. When the larvae are mature they enter the soil. Fruits with only surface feeding injury continue growth to maturity.

Damage is heaviest if the weather is bright and warm during egg laying and when there is a heavy set of fruits.

For control of the apple sawfly consult your State agricultural experiment station.