Apple seed chalcid
Torymus varians (Walker)
Adult is a small, dark wasp with a bright green head, thorax and abdomen with coppery or bronze metallic reflections, brownish yellow legs, clear hyaline wings, and a long ovipositor (A). The larva is white and grub-like with dark sclerotized mandibles, and tapered at the caudal end (B).
NS and southeastern Canada, south at least to PA, and west to MI.
Attacks apple. After overwintering as a larva in the seed, the adult emerges in early summer and the female pierces the flesh of the developing fruit with her ovipositor to deposit an egg directly into a seed. The puncture is visible as a small black dot on the surface of light-skinned fruits, surrounded by a depression. The developing grub feeds in the seed cavity and causes fruit distortion (C). A brown strand of hard, dry tissue extends in to the core, sometimes resembling an apple maggot trail.
Seldom an economic pest in properly managed orchards. Dropped fruit can be collected and discarded in the fall to prevent populations from increasing, and elimination of outside sources of infestation such as wild seedling and crab apples near the orchard is recommended.
The MSU IPM Program maintains this site as an access point to pest management information at MSU. The IPM Program is administered within the Department of Entomology, fueled by research from the AgBioResearch, delivered to citizens through MSU Extension, and proud to be a part of Project GREEEN.