COLLECTING AND REARING. 31 



the flies from the galls is a matter of great importance ; 

 to rear them is not always an easy matter. Probably 

 no rearing case is better than ordinary jelly-cans whose 

 tops have been ground smooth, so that a glass plate 

 may fit them closely. In these cans should be placed 

 sand, which has been thoroughly boiled or burnt to 

 destroy any organic matter there may have been in it. 

 When this has been moistened the pots are fit for use. 



In selecting galls for rearing purposes one point 

 must be kept in view, namely, that only mature galls 

 should be selected to rear from ; for it is practically 

 useless to attempt breeding from half-grown galls, 

 although it must also be said that by keeping some 

 semi-developed galls moistened and exposed to the 

 atmosphere they may grow even when detached from 

 the plant. Still the rule must be, only attempt breed- 

 ing from mature galls. The spring galls do not afford 

 much difficulty. The chief point is to see that they 

 are not kept too moist, and this may be avoided by 

 taking the lid off the case occasionally, because, if this 

 is not done, the galls are very liable to turn mouldy. 

 On the other hand, care must be taken that they do 

 not turn too dry ; if this happens the galls shrink up 

 and destroy the insects. 



The autumnal galls give much more trouble than 

 the spring, as might be expected from the longer 

 period they remain in the galls, especially those which 

 come out in the spring. With these there is only one 

 way of successfully rearing them, and that is to keep 

 them outside, exposed to all the atmospheric changes. 

 In rearing from the galls of the autumnal Neuro- 

 teri it must be recollected that when they fall from 

 the leaves in the autumn they are not fully developed ; 

 but by keeping them outside, and with plenty of air 

 and moisture, they will be devoloped all right in 

 the spring. 



In breeding gall-flies great care must be taken to 

 keep each species in a separate pot, or otherwise grave 

 errors may be made in the records of the rearings 



