Appendices. 103 



if fed on a species of milk-wort, evince a slight variety 

 in colouring and size of moths as compared with 

 those fed on Euphorbia. They must, however, be fed 

 on the plant from the earliest stage, as they only thrive 

 on the food to which they have been accustomed from 

 the first. Some of the earhest specimens are occasion- 

 ally found on the milk- wort, the eggs having been 

 deposited thereon. Those found in January are more 

 likely to thrive on this food than those met with later 

 on, as the Euphorbia, on which they generally feed, is 

 not in its prime till the early spring. 



Great care, patience, and time are required for 

 these most interesting experiments, but the natural 

 advantages of the climate of Teneriffe would greatly 

 facilitate any efforts made, as the variation in tempera- 

 ture is so slight, and consequently the breeding process 

 can be carried on nearly all the year round. Experi- 

 ments of this nature, which might pleasantly be made by 

 those with whom time might otherwise pass slowly 

 in Teneriffe, would probably prove of distinct value 

 to students of Biology. 



