FA MIL Y GEO MET in DAi 



225 



another period of feediiiii". There are probably four or fixe 

 different moults. At the last moult they are two and a 

 half or three inches in length and about as thick as a pencil. 

 They pupate in protected places and remain over winter 

 in this stage, and the moths issue in the early summer and 

 deposit eggs. They are very easily controlled. When 

 clustered during the moulting periods they may be easily 

 gathered and killed. 



Family Geometridse. — The family Geometridw includes 

 the loojxTs. The larva^ have a peculiar arrangement of legs, 

 the abdominal legs being lost, except the last pair, and the 

 movements being made with the thoracic legs. 



Fig. 175. — PalcacrUa vernata: a, male moth, b, foiii lU' moth; both 

 natural size; c, joints of female antenna, d, jumt uf ft-nutle abdomen; e, 

 ovipositor — enlarged. (From Riley, Div. Ent., U. S. Dept. Ag.) 



Canker Worm. — The canker worm is one of the most 

 important of these species economically. These are typical 

 loopers and show some distinct specialization. There are 

 two species closely related, and the>' are known as the fall 

 and the spring canker worms. The spring form appears as 

 an adult in early spring generally before the foliage is 

 expanded on the trees, and the males and females are very 

 different in their characters. The females are wingless and 

 the males have broad, thin wings. The females can gain 

 access to the trees only by crawling up the trunks, and the 

 possibilities of distribution are limited by the distance which 

 the females can crawl. They usually crawl up the trunks 

 of the first tree they reach. The eggs are deposited on the 

 twigs and hatch al)out the time the leaves are fairly opened. 

 The larva' are very destructive. In three or four weeks they 

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