52 BULLETIN 417, U. S. DEPARTMENT OF AGRICULTURE. 



Two larvae that hatched June 24, 1912, were fed almost to maturity 

 and died July 10 and 11, respectively. They were supplied chiefly 

 with pupae of Porthetria dispar, but at the beginning caterpillars of 

 Malacosoma americana were offered. Six caterpillars and 8 pupae 

 were consumed by the first larva and 4 caterpillars and 10 pupae by 

 the second. 



Data secured in New Hampshire in 1909 and 1910 on the feeding 

 habits of the larvae upon Heterocampa guttivitta indicated that the 

 pupal stage of the latter species furnished the most victims of attack. 

 The larvae of frigidum were approaching maturity at the time most 

 of the caterpillars of Heterocampa guttivitta had entered the pupal 

 stage in cells under leaf mold. In these cavities the larvae of frigidum 

 devoured large numbers of them. 



HABITS OF THE LARV^. 



June 21, 1911, five larvae, which hatched June 20, and some of 

 which had fed a little, were tested as to their ability to climb. (PI. 

 III.) Three of them, when placed upon the bark of the tree, clung 

 to it for a short interval, then crawled into crevices and remained 

 there. The other two repeatedly fell from the bark as soon as placed 

 upon it. At 9 a. m., when the experiment was started, caterpillars 

 were left in a cage at the top of the tree for food. At noon all the 

 larvae were on the ground, running around the circle and attempting 

 to climb up the tin in an endeavor to escape. On the morning of 

 June 22 four of the larvae were found in the earth in the circle, but 

 there was no evidence of any having entered the food cage during 

 the night. Two of the larvae were again placed upon the bark of 

 the tree, but fell each time without climbing. On June 23 there was 

 no evidence that the larvae had entered the food cage since the pre- 

 ceding day. June 24 one first-stage larva was again placed upon the 

 tree, but it showed very little inclination to climb, each time hiding 

 under the loose scales of the bark and immediately falling when 

 forced to crawl from under them. June 25 only two first-stage larvae 

 could be found, after examination of all the earth, and one of these 

 was very weak from approaching starvation. Neither had entered 

 the food cage over night. June 26 one of the larvae that was found 

 in the circle the preceding day was dead and the other was almost 

 dead. June 27 one other first-stage larva was found in the earth at 

 the base of the tree, having been overlooked in the search of the two 

 previous days. It was also very weak and was removed and placed 

 in a jar of earth and fed, but died later, presumably from the pro- 

 longed starvation. 



Two were lost during the experiment and it is quite probable that 

 they were devoured by their mates, for the latter lived about six 

 days without other food. A further test was made with larvae of 

 this species in all stages between June 26 and July 6, 1912. They 

 were left inside the circle during this time with food in the cage at the 

 top of the tree but they did not climb there to secure it. They were 

 removed and fed when starvation seemed imminent, or lepidopterous 

 pupae were left on the surface of the earth in the circle for a brief 

 period. They were many times placed upon the bark of the tree 

 but did not crawl in any case more than 6 inches before falling. 

 Three inches upward was the best progress noted. 



