LEPIDOPTEEA (MOTHS). 205 



two pairs of prolegs in the middle of the body ; they are green 

 in colour, with a white streak down the back and a yellow one 

 on each side. The Plusiadse spin a light silken cocoon (3). 



Geometrina. — The Geometers are characterised by the 

 peculiar mode of progress in their larvcS, which have only 

 ten or twelve legs ; the prolegs are never all developed. 

 Very few have twelve legs, fewer still are provided with 

 fourteen. They crawl in a series of "loops," arching the 

 body as they move. "When stationary they are attached by 

 the anal prolegs, generally with the body straight out. They 



Fig. 105.— Silvery Y-Moth (Plusia gamma). 

 1, Ova ; 2, larva ; 3, pupa ; 4, imago. (Curtis.) 



often assume the colour and appearance of the stems and 

 leaves they are found upon : this protective coloration is so 

 marked in some species as to render them almost indistinguish- 

 able. Doubtless this mimicry is to protect them from their 

 enemies, birds and the parasitic Ichneumon flies. The moths 

 have slender bodies and large delicate wings, often beautifully 

 coloured. The pupse are found both under and above ground, 

 and may or may not be enclosed in a cocoon. Most Geometers 

 are crepuscular, but some fly during the day. They are 

 mostly light bodied, and sit with their wings extended in 

 repose, a few with the wings erect like butterflies. Some are 



