Last modified: March 1, 2021, 6:44 p.m.
A very rare species in Belgium, mentioned only from Brussels and Leuven (VB), nowadays (2000) possibly extinct. The species has declined sharply because rye, the main food plant, has become rarely planted in Belgium.
Eggs are characteristically deposited on interior wooden walls, ceilings and straw bales or piles in outbuildings and on grasses from June through September. Eclosion occurs bimodally with around fifty percent of current season eggs hatching in late June and July. The remainder overwinter and hatch in February and March.
Larvae are found in April and May. Light yellowish white body, prothoracic plate blackish brown, anal plate light brown.
First instar larvae typically mine leaves, later stadia are stem borers.
The young caterpillar mines in a leaf, after about a week they drill into the stem of the food plant. Young caterpillars are sometimes spread by the wind. In May and June, the larva pupates in a whitish flimsy cocoon between the leaves or in cracks of the food plant.
The adults are flying low to the ground at dawn. They are sometimes observed indoors, especially in barns.
The adults fly from June to August.
The larvae feed mainly on Secale cereale (can reach pest status on that crop), but also on a variety of other grasses like: Lolium, Bromus, Triticum, Poa or Festuca.