x1] Flies 145 
prevent them from hatching. All diseased stumps 
should be burned and the soil should be turned under 
as deeply as possible as soon as the crop is removed. 
It is chiefly in gardens where cruciferous crops are 
grown every year that this pest proves most destruc- 
tive. When the crops are rotated the fly has great 
difficulty in living from one crop to the next. 
The carrot fly (Psila rosae) and the onion fly 
(Phorbia cepetorum) have life histories very similar to 
the cabbage fly. 
The damage done by the former may be reduced by 
keeping the carrots earthed up as tightly as possible. 
In the case of the onion fly dusting with a mixture 
of two parts of lime to one of soot is said to be useful. 
All plants attacked together with the maggots should 
be destroyed. 
Leather Jackets (Tipula sp.). 
Leather jackets are the grubs of the flies which are 
commonly known as daddy longlegs or crane flies. 
There are several different species which injure crops, 
all very similar in appearance and in the damage 
which they do. 
It is the larvae or grubs which feed on nearly all our 
crops and often do enormous damage to grass land and 
roots. Clover leys and corn may also suffer consider- 
ably. These grubs are of a dirty or smoky colour and 
somewhat difficult to see in the soil. They vary from 
4-1} inches in length, the longer ones being about 
4 inch across, the others correspondingly thinner. 
They are legless but possess a definite retractile head 
with a pair of jaws. The tail end is thick and carries 
six conical papillae. Their skin is tough and wrinkled, 
P. F. 10 
