March, 1907.] FlELD : NOTES ON DaTANA ROBUSTA. 55 



they came. Some time in March, ray son, who had evidently been 

 doing some thinking on the subject, took a trowel and dug around the 

 base of a Rhus where the leaves gave evidence of having furnished the 

 necessaries of life to a colony of something, and was rewarded by 

 unearthing several pup^. The digging was continued at odd times 

 until we had about fifty. These were placed in earth in two cigar 

 boxes and the boxes were placed in a large breeding cage. Of course 

 I knew(?) I had G. medusa. On September ist the first adult ap- 

 peared, but it was not G. medusa by any means. A friend owned 

 Holland's " Moth Book " and he decided it was Dataua integern'ma. 

 Later he expressed doubt on his first statement and thought it might 

 be D. californica. If it was the latter I knew it would be of more 

 value for exchange purposes than the former. To settle the question 

 I forwarded two specimens to Dr. Dyar which were identified as D. 

 robusta. If my memory serves me rightly, the larvje appeared about 

 September 15th. While very young and up to the time that they 

 reach at least one-third of their growth they cluster closely, but after- 

 ward they separate, each going by itself. The thought came to me, 

 how do they get the necessary food while clustering ? Do they separate 

 in the darkness to feed and return to herd together in the day ? I am 

 very much of the opinion that this is correct. That they feed in the 

 night is true. In fact I think that they are more active after nightfall 

 than in day time. One can hear them feeding very distinctly two or 

 three feet away from the breeding cage. When nearly grown they 

 feed day and night. On attaining their full growth they descend and 

 enter the ground to pupate. The soil under the Rhus where I found 

 the pupse was for four or five inches in depth, composed almost en- 

 tirely of decayed leaves and small branches that had accumulated for 

 years, making it very light and porous. This rested on a hard subsoil 

 of clay. The larvse would usually go down to this hard subsoil to 

 pupate, but do not enter it except so far as to make a little bed to lie 

 in. I would mention here that the pupas are perfectly naked and have 

 no covering whatever, while in that state. A considerable number 

 would not reach the subsoil, but pupate in the light top soil. As I 

 stated I had fifty pupte but through ignorance or carelessness which 

 probably created unnatural conditions I succeeded in obtaining only 

 about a dozen adults. 



