CANKER WORMS. 78 1 



laid on the trees before the middle of November, and only a 

 few males could be found. The females of both species are 

 without wings, and must necessarily crawl up the trunks of the 

 trees to lay their eggs on the twigs. Males, on the other hand, 

 are provided with wings, and fly short distances at night and 

 even during dark cloudy days. Many of the adults, however, 

 do not emerge until March, and this is especially the case when 

 the ground freezes early in the fall and does not thaw out until 

 late in the winter. 



In Saybrook, where the elm trees were considerably damaged 

 by canker worms in 1907, sticky bands were applied about March 

 1st, 1908, as it was supposed to be the spring species that caused 

 the injury; but it was found later that the fall species was the 

 more abundant and that enough eggs had already been laid 

 before the application of the sticky bands so that the trees were 

 quite badly eaten by canker worms. 



The eggs, though deposited in late fall or in early spring, hatch 

 in Connecticut during the last of April or the first few days of 

 May. 



The young larvae are at first very small, and they soon begin 

 to feed on the tender unfolding leaves. They eat holes entirely 

 through the leaves, or in fact devour all of the green tissue, leav- 

 ing nothing but the veins. Later, as the foliage becomes firmer 

 and more leathery, they often leave the greater portion of the 

 network, especially in case of the apple (shown on Plate XLV) 

 which turns brown in June and looks as if a fire had gone 

 through the orchard. 



The caterpillars feed from four to five weeks, during which 

 time they spin down on threads of silk when disturbed, and molt 

 three times. They then go to the ground and transform to the 

 pupa or chrysalid stage. By June 6th, 1908, all canker worms 

 had gone into the ground to pupate. They then remain in the 

 pupa stage until the late fall, when the adults of the fall canker 

 worm begin to emerge in November, and during warm days for 

 two months they may be seen clustering on the trunks of trees ; 

 but some do not appear until March and April, at the same time 

 that the spring species comes forth. There is but one generation 

 each year. 



Canker worms are always rather local in their attacks, and the 

 writer has often seen large orchards defoliated in certain localities. 



