42 Agkioultitral Experiment Station, Ithaca, N. Y. 



After the third moult the larvse fed but little; one or two moulted 

 the fourth time. When this stage is reached, the larvte seem to know 

 instinctively that they have reached that point in their development 

 when it is necessary for them to make preparations to go into winter 

 quarters, even though it be several weeks yet before the leaves become 

 unfit for food or fall from the trees. 



Hibernation. — Previous to 1885 the Bud Moth was supposed to 

 pass the winter in the ^^g state as recorded in 1840 by Schmidberger. 

 In 1885, however, Mr. J. Fletcher, in his Report as Entomologist to the 

 Department of Agriculture of Canada says: "I do not know for cer- 

 tain the life history of this little moth, but believe that it passes the 

 winter on the branches of the apple trees, protected by a covering of 

 silk. I have found small brown larvfe hibernating in this manner at 

 Kentville, N. S. The size of the (caterpillar in the spring when it 

 attacks the buds also points to the probability of this view." Prof. 

 Fernald says: "Late in the fall the silken web is quite heavy and 

 thick, and the larva deposits its excrements in little pellets in the form 

 of a tube, under the web, within which it hibernates during the win- 

 ter." In August, 1891, Dr. Lintner stated (Can. Ent., XXIII, 231) 

 that: "He had believed that eggs were deposited in the month of 

 April by the parent moths, from some imperfect and denuded speci- 

 mens that had been captured fluttering about the trees at this time, 

 and which seemed to be that species. Some of the larvte which he 

 had hatched from the eggs in June had attained such size in early 



be after any future moult. This method has been found to work surprisingly 

 well in practice here at the Insectary. Mr. Dyar has found but few exceptions 

 in his work. It requires careful measurement with a compound microscope, 

 however, and the real diameters frequently vary from the calculated, but 

 rarely more than .05 mm. 



The heads of the Bud Moth larvte were found to measure .225 mm. when 

 first hatched. In a few days a cast head was found under a web. The diam- 

 eter of the head of the larva in the tube was .288 mm. From the ratio 

 between these diameters calculations were made of what the diameters of the 

 heads would be after the other moults. But what would be the last term of 

 the series ? It so happened that a larva which had spun its cocoon but had 

 not yet changed to a pupa was available. The diameter of the head of this 

 fully matured larva gave the last term. Surprising as it may seem, tlie calcu- 

 lated seventh term lacked only .06 mm. of the real diameter of the larva's 

 head. The calculated <liameters after the second moult were as follows: .368 

 mm.; .471 mm.; .603 mm.; .772 mm. and .99 mm. The real diameters thus 

 far obtained from measuring the heads of the larvae are : .363 mm.; .43 mm.; 

 .56 mm. and 1.05 mm., leaving that after the fifth moult to be determined. 

 The diameters after hatching and after the first moult are not included in 

 these figures. They were obtained by measurement and formed the basis for 

 the others ; they were .225 mm. and .288 mm. 



