208 OHIO EXPERIMENT STATION: BULLETIN 332 



readily available the cocoons may be spun on any part of the tree 

 even upon the smaller branches, where one finds them usually with 

 a leaf drawn down and bound into the cocoon. In cases of severe 

 attack, the tree may be almost plastered, as indicated by Plate XVII, 

 Fig. 3. This pernicious habit of spinning high up in the tree, as 

 will be seen later, renders control measures much more difficult. 



After the completion of the cocoon, the larva transforms into 

 the pupal stage. In the pupal stage the sexes can be distinguished 

 with comparative ease on account of the difference in size. The 

 male averages about nine-sixteenths of an inch in length and the 

 female eleven-sixteenths of an inch. In color both sexes are vari- 

 able, ranging from yellowish green to very dark brown ; usually they 

 are mottled and two distinct spots of granular material are to be 

 seen on the dorsum. 



The greatest difference is apparent, however, in the appearance 

 of the adult moths. The male is a grayish brown moth with a wing 

 expanse of about li/i inches. The general shape of the body is 

 that of the average typical moth. (See Plate XVIII, Fig. 3.) The 

 female, however, is either entirely without wings or with but small 

 rudimentary stubs, and is light gray in color. (See Plate XVIII, 

 Fig. 2.) 



The eggs are deposited in masses of from 100 to 500 each, 

 usually on the outside of the female's empty cocoon. (See Plate 

 XVIII, Fig. 1.) Covering the eggs is a frothy substance which 

 in time becomes brittle and forms an effective protection. The 

 individual eggs are nearly spherical and average about one-twenty- 

 fifth of an inch in diameter. 



Life history. — The winter is passed in the egg stage. In the 

 latitude of Ohio the young hatch in late May. A month or a little 

 more is required to complete the larval growth; thus in late June 

 or early July the cocoon is spun and transformation to the pupal 

 stage occurs. 



The pupal period lasts for 10 days to 2 weeks, whereupon the 

 adults emerge. Mating occurs with the female clinging to the old 

 cocoon, and soon afterward the eggs are discharged in the mass as 

 previously described. 



About 2 weeks after their deposition the eggs give issue to the 

 second brood of caterpillars, which in their turn pass through a 

 life history similar to the one just described. 



In Ohio there are two full broods, with the second usually the 

 larger, and in the southern part of the State a third, or at least a 

 partial third brood, occurs. The eggs of the last brood of the sum- 



