A small number of Agromyzidae species form galls to feed within. These include Agromyza erythrocephala Hendel, 1920 (stem gall on Vicia), Hexomyza spp, Melanagromyza cunctans (Meigen, 1830) (stem gall on Lotus) and Phytomyza wahlgreni Ryden, 1944 (gall on Taraxacum).

The image below shows three larval galls of Hexomyza simplicoides (Hendel, 1920) on a first-year shoot of Salix caprea.

Hexomyza simplicoides (Hendel, 1920) galls on Salix caprea stem © Barry P. Warrington

When a gall is opened, a larva or puparium may be found inside. The image below shows a cross-section of a Hexomyza simplicoides gall, where a larva is present within the feeding chamber;

Cross-section of a Hexomyza simplicoides gall with larva present inside feeding chamber © Barry P. Warrington