130 Flies [cH, 
may eat through it. The plant responds by forming 
other shoots and so we get a tufted appearance. 
Diseased shoots may be found together with healthy 
ones on the same plant, especially in mild attacks. 
Later in the season small brown cases are present 
instead of the maggots. These are easier to find 
because of their colour. These pupa cases of the fly 
are slightly shorter than the maggots, cylindrical, 
and of a reddish-brown colour. The two wart-like 
spiracles are still present at the posterior end, and the 
black jaws of the larvae can often be seen through the 
case (see Fig. 39 B). 
If we put some of them in a bottle, the mouth of 
which is covered with muslin, the frit flies will hatch 
out in July. This is precisely what happens in 
nature, and at the end of July large numbers of these 
flies may be found on the ears of oat plants. They are 
very small and measure less than 4 inch in length. 
They are black and shiny (see Fig. 39C). 
The flies which are found in July lay their eggs in 
the ears of young oats or barley, or on the young 
shoots of grasses. The maggots which hatch out from 
the ears of oats or barley live on the developing grain, 
causing it to be gnawed and shrivelled. Pupa cases 
may be found in infected ears just before harvest. 
The maggots that hatch out on grasses feed on the 
young shoots in the same manner as the maggots 
already examined feed on the young oats. The third 
brood of flies appear in August and September, many 
of them after the grain has been harvested. They 
have been found in swarms in granaries containing in- 
fected grain. This brood lay their eggs on wild grasses 
or winter corn, and the maggots which hatch from 
