1924 ENTOMOLOGICAL SOCIETY 47 



instar (fall observation) 21 days, the third (spring observation) 13.11 days, and 

 the fourth (spring observation) 17.01 days. A very great increase in food 

 consumption is noticed after the second moult. They winter in all four larval 

 stages as well as in the egg stage. 



The Pupa. The larvae cease feeding a day or two before they commence 

 spinning cocoons, which operation requires one or two days. The usual location 

 for the cocoon is just below the surface of the soil, but it may be over an inch 

 deep in the soil, where there is lack of moisture, or on the surface under debris. 

 The cocoon is not woven from one continuous thread, the silk being cut off at 

 each end, at a length of from three-eighths to five-eighths inches. A rest is always 

 taken after the spinning of each thread (for about the same length of time as the 

 work) and a new supply of silk material is taken before resuming spinning. 

 Sometimes the supply appears to run low, when the larva kneads the underside 

 of the last two body segments with its head, as if forcing the secretion to the 

 opening. This substance is very adhesive, adhering to the sides of the pupal 

 chamber and to the threads already spun very securely. Curiously enough it 

 does not seem to adhere to the body of the larva, when too large a supply is 

 taken. Slightly over six inches of silk is spun in one hour. The prepupal period 

 lasts from three to eight days and the pupal from five to thirteen days. 



The Adult. After the pupal skin is shed the adult remains within the 

 cocoon for one to four days. With specimens emerging in vials not supplied 

 with food, the cocoon is always eaten, but this is not the case in the field where 

 there is an abundance of food, only sufficient being eaten from one end to permit 

 the beetles to emerge. After emergence they feed regularly for two weeks, then 

 become dormant until August. The feeding habits of the adults are somewhat 

 different during oviposition, for then the petioles as well as the blades are eaten. 

 There appears to be only one generation in Western Ontario, the beetles dying 

 soon after oviposition is completed. 



The spread to new fields occurs during the latter part of August. On a 

 bright sunny day the beetles may be seen in flight and running rapidly from 

 plant to plant over the bare spaces on the ground surface. 



Although hundreds of larvae have been reared and collected from the field 

 we have never observed any natural parasite. In years of excessive abundance 

 the outbreak seems to be controlled naturally by a fungous disease known as 

 Empusa sphaerosperma. 



WINDS AND GIPSY-MOTH SPREAD 



E. P. Felt, Chief Entomologist, Conservation Commission, 



Albany, N.Y. 



It is well known that wind-spread is an important factor in the dissemination 

 oftthe gipsy moth (Porthetria dispar Linn.) . The earlier investigations in eastern 

 Massachusetts, by agents of the United States Bureau of Entomology, have 

 shown that the recently-hatched caterpillars may be carried considerable dis- 

 tances — as much as twenty or twenty-five miles over water. 



The proposed barrier zone in which the gipsy moth should not be allowed 

 to establish itself made it very desirable to study the winds of western Massa- 

 chusetts and eastern New York during the period when conditions were favour- 

 able for wind-spread. 



