302 



Mr. Foulton' 8 fart li €7' experiments upon 



EXPEBIMENT I. 



Dark surroundings. 



May 28. — 3 of the larvit men- 

 tioned above were introduced, abun- 

 dant dark twigs being intermixed 

 with tlie food. 



June 5. — The larv* compared 

 with those of II., and they were 

 certainly rather darker than the 

 latter. Another small larva was 

 introduced, hatched May 25 or 26. 



June 14. — Another comparison 

 was made, these larvae being dis- 

 tinctly, although not strongly, 

 darker than those of II. 



June 17. — Again compared, with 

 the same results : a very fair com- 

 parison could be made between the 

 '6 largest of this and the 2 largest of 

 Experiment II. 



June 25.-2 larvae spun up. The 

 small larva introduced June 5 is 

 now 25-25 mm. long, and very dark, 

 much darker than that in II. 



July 11. — The large larva pupated 

 much earlier. The small one is now 

 mature. The difference is very dis- 

 tinct, but not to be compared with 

 that of C. elocata, in which the dark 

 larva is far darker, and the light 

 larva far lighter, showing greater 

 susceptibility in both directions. 



Experiment II. 

 Green surroundings. 



May 28. — 3 of the larvae described 

 above placed among leaves and 

 green shoots only. 



June 5. — Another small larva 

 introduced, hatched May 25 or 2(5. 



June 17. — 1 has spun up. The 

 difference between the large larvse 

 here and those of I. is not great, but 

 it is all in the same direction. 



June 25. — 2 larvae spun up. 

 small larva is 31*4 mm. long. 



The 



July 11. — The remaining larva 

 spun up at this date. 



The development of the larvse is not remarkably rapid, 

 like that of C. sponsa. The degree of susceptibility 

 appears to be about the same as in this latter species. 



5. Experiments in 1889 upon Catocala elocata. 



Eggs were kindly supplied by Mr. William White. 

 The very few larvae which hatched were arranged in 

 two lots, as in the case of C. electa. The food-plant 

 employed was poplar {Populus nigra). 



Experiment I. 

 Dark surroundings. 



Experiment II. 

 Green surroundings. 



June 14. — 1 larva introduced ; 

 hatched May 27, and 23-0 mm. long 



June 25. — The larva was mucli 

 darker than that of II., its length 

 being 32-5 mm. Another larva in- 

 troduced ; hatched June 5, and 

 22"2y mm. long. It was very light 

 in colour, as up to this date it had 

 been surrounded by leaves alone, 

 viz., under the conditions of II. 



June 14. — 1 larva introduced ; 

 hatched May 31, and 21-0 mm. long. 



June 25. — The larva was 29-0 

 mm. long. The strong difference 

 between this and that of I. was thus 

 produced in 11 days. Another larva 

 introduced ; hatched June 8, and 

 13-0 mm. long. It was much darker 

 than that introduced mto I., but 

 this was partly due to its youth. 



