132 Flies [CH. 
these feed on the shoots of their host and eventually 
change into pupae. From the pupa cases next season’s 
first brood of flies appear in April and May, ready to 
lay their eggs on any young oat plants, or in their 
absence other suitable hosts. The frit fly is capable of 
attacking only young oats so that those which are put 
in early and grow quickly through the early stages 
have a good chance of escaping an attack. The frit 
fly has three broods during each season and it is only 
in the maggot stage that damage is done. The first 
brood feed on the shoots of oats and sometimes on 
related plants. The second brood feed on the grain of 
oats and barley or on the shoots of grasses, and the third 
brood feed on the shoots of winter corn or grasses. 
By far the largest amount of damage is done by 
the first brood. In some seasons the attack is much 
worse than in others, this being largely due to the 
weather conditions of the autumn and spring previous 
to the attack. 
Remedial Measures. 
No means are known by which the attack can be 
stopped when the crop shows itself to be attacked. 
It is possible however to prevent future attacks to a 
large extent. We have seen that the damage done by 
this fly is chiefly to late sown oats, and consequently 
our best means of prevention is to get them in as early 
as possible. In 1912 a field of oats in Norfolk sown the 
second week in April was ruined by frit fly, whereas a 
neighbouring field sown the second week in March was 
almost free from it. A careful search however revealed 
the presence of a few specimens. This example will 
