Apple sawfly larvae attack apples during the fruitlet stage in late spring to early summer. Affected fruit often drop off in June. Although sawflies are as widespread as the codling moth, the damage they cause is different and should not be confused. Codling moth maggots are usually found inside fruit later in the summer.
What Is Apple Sawfly?
Adult apple sawflies are small winged insects active from late April to May. They can often be seen entering apple blossoms, where they lay eggs at the base of the flowers. These eggs hatch soon after the petals fall. The larvae resemble short caterpillars, around 4–5mm long, with dark brown heads and pale brown bodies.
Once hatched, the larvae tunnel just under the skin of developing apples, creating thin scars. As they grow, they burrow deeper into the fruit, which causes early fruit drop. If a larva dies before reaching the core, the apple can survive but will show a shallow scar where feeding occurred.
When fully fed, the sawfly larva measures about 10mm long with a brown head and creamy white body. Each larva can damage three to five fruitlets before dropping into the soil, where it overwinters and pupates the following spring.
Symptoms of Apple Sawfly
From late May through June, damaged fruit show small holes or tunnels beneath the skin. These apples usually fall early during the natural June drop, when trees shed excess fruits. If damage is only partial, the apples may remain but appear scarred or misshapen.
Because apple sawfly and codling moth occur around the same time, they are often confused. To identify sawfly activity, hang apple sawfly traps in your trees from April to June. The traps are simple to use and help monitor infestations without pesticides.
Reducing Damage from Apple Sawfly
There are several effective ways to reduce damage and interrupt the sawfly life cycle:
- Fit grease bands on fruit trees to stop overwintering pests from climbing the trunks in spring.
- Apply a tree wash at the end of the season to remove dirt and debris where larvae or eggs might overwinter.
- Hang apple sawfly traps between April and June to catch adults and monitor activity.
- Pick off and dispose of damaged fruit early to prevent larvae from spreading to healthy fruit or entering the soil to pupate.
Summary
Apple sawfly can cause scarring, fruit distortion, and premature fruit drop. Regular monitoring, good hygiene, and timely use of traps and tree care products will protect your trees from ongoing damage and reduce the need for chemical control.