The adult apple sawfly is up to 5 mm (0.2 in) long with a brownish-black head and thorax and a brown abdomen.

The larva is a caterpillar-like grub with a brown head and white body, growing to about 10 mm (0.4 in) when fully developed.

It was first detected in North America on Long Island, New York, in 1939, and has since spread across the northeastern United States, and into Canada, reaching Quebec by 1979 and Ontario by 1987.

As they grow larger, they tunnel outwards and move into an adjoining fruitlet, making a large entry hole which gets clogged with brown, sticky frass.

Sticky traps can be used to catch adult sawflies to monitor the levels of attack and assess whether pesticides would be economical to apply.

These treatments may also control plum curculio (Conotrachelus nenuphar) as part of an integrated pest management programme.

[8] Research has shown that quassin and neoquassin, extracted from Quassia amara, can provide control of H. testudinea in organic agriculture; commercial formulations are used in Germany and Switzerland, but are expensive.