88 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 11 
The larvae pass the winter within this scattered grain in various 
stages of development between the half-grown and mature larval 
stages. In the early spring the immature larvae again start to feed 
and complete their growth; the fully grown larvae remain quiescent until 
shortly before the pupation period. 
The Cocoon. —During the middle and latter half of May the 
larvae start to spin their delicate silken cocoons within the wheat grains. 
The space thus occupied by the cocoon is cleared of all frass particles, 
this generally being packed to one side of the hollow grain, or some¬ 
times it is cast out of the grain through a small hole which is gnawed 
through the side. Further preparation for final exit is made by gnaw¬ 
ing almost through the distal end of the grain (the end opposite the 
plumule), leaving only a very thin circular membrane. The cocoon 
proper is thin and delicate, consisting of but a single layer of fine white 
silk which covers the walls of the cavity. After spinning the cocoon 
the larvae remain quiescent for two to three days before pupation 
occurs. 
Pupation. —At York, Pa., pupae were found as early as May 10, 
but were not abundant until after May 20. 
The duration of the pupal period as observed at York during late 
May and early June varied from ten to seventeen days, having an 
average of thirteen days. When first formed the pupae are light honey 
yellow, but soon turn to a golden brown as they harden. Before the 
final ecdysis takes place the developing moth is easily seen through the 
transparent pupal sheath. 
Emergence and Habits of the Moths. —The moths emerged 
throughout the day, but seemingly a larger per cent leave their cocoons 
during the morning. Escape from the cocoon is made by pushing 
against the thin exit membrane, which parts at the margin, and lifts as 
a hinged lid. The expansion of the wings is accomplished in fifteen 
to twenty minutes, and feeble flight is possible within an hour after 
emergence, but as a rule flight does not take place for several hours. 
The moths are crepuscular in habit, being most active in the dusk 
of early evening and morning. At these times they may be observed 
mating and depositing their eggs. 
The moths which develop from the hibernating larvae constitute the 
first brood, or spring generation, which causes the initial larval damage 
to the season’s wheat crop. This brood appears toward the end of 
May, and seems to reach its maximum numbers between June 5 and 15. 
After June 20, moths are not common. 
Oviposition. —As the period of oviposition is indicated by the 
period of the moth flight, it is worthy of note that this is also coincident 
with the heading of the wheat in the fields. In York, Pa., and the 
