Insects Injurious to the Apple. 



159 



green all over and the abdomen larger and broader than the thorax, 

 and small rudiments of wing buds appear (Fig. 129). 



This is the first nymphal or pupal stage. Like tlie larva it has a 

 long thread and waxy globule and becomes still further covered with 

 white waxy threads and fine curled hair-like particles. 



The third change of skin takes place in from eight to fifteen days 

 and the wing rudiments become more pronounced. After this moult 

 the filament and fine curly threads are mostly pale blue. 



The nymphal stages are usually found on the leaves, the fine 

 filaments seem to hold two leaves together and thus shelter the 

 " suckers." Often several nymphs are 

 found close together between the two 

 leaves. 



Previous to the moult, the nymph 

 fixes its beak firmly into the leaf and 

 then the skin splits and the winged adult 

 emerges and leaves its cast skin firmly 

 attached to the leaf (Fig. 130). 



The whole cycle, from the hatching of 

 the egg to the bursting forth of the imago, 

 takes from four to six weeks. 



The colour of the pupiB varies, those 

 found between the leaves are yellower 

 than those which are free on the surface, 

 which are normally green. The antennae 

 are very marked, being darker at the tips 

 which are bifurcated, the same as in the 

 winged adults. 



As far as we know at present the 

 apple is the sole food plant of this 



Psylla. One year I found numbers of it on a hawthorn hedge 

 near some apple trees in my garden, together with some Psijlla 

 cratmgi, but I find tliey do not breed on the hawthorn and that they 

 evidently only go there for temporary shelter. They may also be 

 found in the winged state on pear and plum and currants when 

 mixed with apple, but they are there only as casual visitors and not 

 for depositing their eggs. As soon as the male has fertilised the 

 female he dies, but the female lives for some days after. 



[A'. Fuiiey. 

 FIG. 133.— YOUNG LARV.E OF APPLE 

 SUCKER WAITING TO ENTER BUDS. 



Prevention and Treatment 

 The prevention of the Apple Sucker is no easy matter, owing to 

 their hatching out irregularly. Spraying to kill the young is very 



