128 Flies [CH. 
field very few ears of oats are formed as the shoots 
which would normally bear the ears are killed. 
Diseased oats tiller freely and each shoot attacked 
becomes thickened at its base and remains stunted, 
usually from 4 inches to 1 foot in height. An oat plant 
in which all the shoots are attacked looks like a tuft 
of very coarse grass (see Fig. 38). The young shoot is 
yellowish or brownish and may be in a state of decay. 
The older leaves may appear quite healthy or take on 
a reddish appearance. 
The fly attacks oats and occasionally barley, rye, 
wheat and grasses. It is usually spring sown oats that 
suffer, but winter oats are also occasionally attacked. 
By far the greatest amount of damage is done to 
late sown spring oats. Those sown early in March in 
a good seed bed are practically free from the disease, 
and it is only by a careful search that an infested 
plant can be found. On the other hand those sown 
late in April are sometimes so badly attacked that 
less than 10 per cent. of the ordinary amount of 
ears are formed. 
If we carefully examine a diseased shoot about the 
beginning of June we shall find a small maggot in the 
middle of the plant. This is the larva of the frit fly, 
and is about 4 inch long when full grown. It has a 
somewhat transparent, shiny, fleshy appearance. Its 
body is segmented and legless. The anterior end, 
which is somewhat pointed, is easily recognized by a 
pair of almost black jaws which are capable of being 
protruded. Near the front end on each side is a 
branched spiracle. The posterior end is blunt and 
possesses two wart-like spiracles (see Fig. 39). 
The maggot eats into the stem and in many cases 
