1921.] 



The Raspberry Gall Fly. 



649 



are opened they are found to be infested with numbers of larvae, 

 the usual number varying from fifteen to twenty, though as 

 many as thirty have been recorded. The interior ol the gall 

 varies in colour from very dark blue to black, the centre being 

 quite spongy in texture. The larvae are readily seen, their 

 orange-red colour making them very distinct against the dark 

 interior. 



The Larva is maggot-like and measures up to .1 in. in.) 

 in length at maturity. Feeding goes on through the late 

 summer, autumn and winter. Where galled shoots were placed 

 with their bases in water the larva? became restless and com- 

 menced leaving the galls; they settled down quite normally, 

 however, when the shoots were removed and placed in the soil, 

 where the water supply was more in keeping with their natural 

 requirements. 



The Pupa is about .08 in. (^-^ in.) long and of the same colour 

 as the lai-^'a. Pupation takes place in March and April in the 

 galls, and before emergence the pupae woi'k themselves to the 

 outside of the galls. After the exit of the flies the pupal cases 

 may be seen protruding from one-half to three-quarters of their 

 length out of the gall. Flies reared from galls kept at Long 

 Ashton emerged between 13th April and the end of that month. 

 Theobald, however, states that the flies hatch from May on into 

 Jime. This difference is undoubtedly accounted for by the 

 forcing effect of laboratory conditions. 



The Adult is typical of the Cecidomyidae. Its body, wings 

 and limbs are covered with soft pubescence, and the dorsal 

 surface of the abdomen is banded alternately with black and 

 white, the pubescence on the ventral surface being uniformly 

 black. The articulations of the wings and the coxal joints of the 

 legs are yellowish in colour. The front of the thorax, which is 

 almost hoodlike, is sparsely covered with rather coarse, almost 

 bristle-like, greyish or yellowish down. The head is small and 

 appears tucked under the thorax, and bears short, black 

 antenna\ which are generally pointing downwards and forwards. 

 The wing expanse is approximately .2 in. (-1- in.). 



Egg-Laying. — According to Theobald, egg-laying takes place 

 in Juno, tlic eggs being deposited at the base of the buds and 

 side shoots. They hatch in about eight days and give rise to 

 larvip which burrow into the rind and feed, setting up tlie irrita- 

 tion which results in the formation of the galls. The effect of 

 infestation is a stunting of the canes, wliich may bear no fruit 

 rnd few leaves. 



