370 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 7 



pupated in the fifth stage, while the remaining 235 passed into the sixth 

 stage and developed female pupse. 



Available information bearing on this subject in other species is 

 limited, although Doctor Dyar as quoted in Packard's text-book, p. 

 618, says that the average number of molts of lepidopterous larvae is 

 five, but six or seven stages are not infrequent. In rearing larvse of 

 Hemerocampa (Orgyia) gulosa Hy. Ed., he found that the males molt 

 three or four times; the females always four. He also notes in Psyche, 

 Vol. 5, p. 422, 1890, a somewhat similar variation in Hemerocampa 

 (Orgyia) definita Pack. In this species the female larvse requTre one 

 more stage than the male. 



In the First Annual Report of the State Entomologist of Missouri, 

 1869, p. 145, there is an account of Professor Riley's observations 

 using larvse of Hemerocampa (Orgyia) leucostigma S. & A., which was 

 as follows: "About the middle of the month of May these eggs 

 began to hatch. . . . Six days after the second molt, the third 

 molt takes place with but little change in the appearance of the 

 caterpillar. Further than that, the different colors become more 

 bright and distinct, and different tufts still larger. Up to this time 

 all the individuals of a brood had been alike, and of a size, so 

 that it was impossible to distinguish the sexes. Six days from the 

 third molt, however, the males measured not quite f inch, and begin 

 to spin their cocoons, while the females undergo a fourth molt about 

 this time, and in about six days more they also spin up having acquired 

 twice the size of the male when he spun up. " 



There seems to be little doubt but that the female larvae of this 

 species require an additional stage under normal conditions, but when 

 subject to unnatural conditions this rule may not hold. That the 

 larvse of this species may vary considerably when fed sparingly is 

 evidenced by the result of Miss Murtfeldt's experiment, which was 

 carried on under the direction of Doctor Riley. In rearing these 

 caterpillars and feeding them only enough to sustain life both males 

 and females molted four times. ^ 



On several occasions the scarcity of certain foods necessitated the 

 stinting of caterpillars used in our experiments, but regardless of this 

 fact the females passed through an additional larval stage. 



In the March number of the Entomologists Monthly Magazine, 1887, 

 V. 23, p. 224, there is an article by Dr. T. A. Chapman on the molting 

 of Notolophus (Orgyia) antiqua Linn., and on rearing its larvse he says: 

 " The variability of molting occurs in the later stages. When we come 

 to inquire into the significance of this variability, we meet at once 

 with a very decided fact, and that is, that those that molt only three 



1 The Amer. Nat., Sept. 1873, V. 7, No. 9, p. 513. 



