GALL
The weakly swollen culm [aboveground stem] has, just above a node, one or more shallow oval depressions. They are not covered by the epidermis, but generally lie within a leaf sheath. In each a single, 3 mm long, larva is found, that is almost hyaline. Pupation within the gall: the larva forms a dark reddish brown puparium. Usually bivoltine. Heavily infested plants die off.

Only in the first and second instar the larva does feed. The third instar larva remains immobile within the dried larval skin of the second instar, a puparium, that functions as a cocoon. Before the definite pupation the larvae has to reverse its position to head upwards within the puparium; in this way the emerging imago will be able to leave the gall.

HOST PLANTS
Poaceae, oligophagous

Cynodon dactylon; Elytrigia repens; Holcus lanatus; Hordeum murinum, vulgare & subsp. distichon; Phleum pratense; Poa nemoralis; Secale cereale; Triticum aestivum.

mainly in cereal crop species, wheat in the first place.

- Willem N. Ellis: (2021) Plant Parasites of Europe^©

Reference: https://bladmineerders.nl/parasites/animalia/arthropoda/insecta/diptera/nematocera/cecidomyiidae/cecidomyiinae/lasiopteridi/oligotrophini/mayetiola/mayetiola-destructor/