INSECTS. 



151 



The Silver Y Moth (Plusia gamnna). 



Moth : About | of an inch long ; span of wings 

 1^ inches. Dark grey, mixed with a reddish tint, and 

 darkly marbled. About the middle of the fore wing 

 there is a very obvious gamma (y), or Y-shaped mark. 

 Hind wings bright brown at the root, darker at the 

 margins, with a whitish fringe. A crest of hairs on 

 the dorsal side of the thorax. Caterpillar : 12-legged. 

 It bends its body like a looper (Fig. 102). Length 

 1 to 1^ inches. Ground colour green ; but there may 

 be variations in this from a dirty green to a brownish 



Fig. 102. — The Silver Y Moth (^Plusia gamma), with caterpillar and pupa. 



colour. Six fine longitudinal lines on the back, and 

 a yellowish line above the legs. The caterpillar is 

 almost naked, only possessing a few small, isolated 

 bristle-like hairs. Habits : At least two generation^, 

 and sometimes as many as five in two years. The 

 Silver Y Moth generally hybernates as a half -grown 

 caterpillar, but sometimes also in the pupa, or moth 

 state. The caterpillars may therefore be met with 

 the whole year ; but they are usually most abundant 

 from the end of June to the middle of August, and, 

 under favourable conditions, may become an agricul- 

 tural pest. They devour the leaves of almost all wild 

 and cultivated plants (except grasses, corn, and trees), 

 and are especially fond of leguminous plants (peas, 

 vetches, clover), flax, beet, rape, cabbage, and buck- 

 wheat. The moths mostly appear in May, but also 

 in July, and later on in the summer, especially on 



