on colour-relation. 227 



3. Notes on larva of Catocala fraxini. 



On May 21st, 1890, twenty-four fertile ova of the 

 Clifden Nonpareil Moth {Catocala fraxini) were supplied 

 to me by Mr. E. Edmonds, of 31, Park Street, Windsor. 

 The larvffi began to hatch out almost immediately on 

 arrival, and by May 26th seven had emerged from the 

 eggs. These were placed together in a cylinder, like those 

 used for other species, and were supplied at first with 

 the common ash. This food-plant was continued for a 

 week, but the larvae refused to eat any of it, and four 

 died. This was curious, as ash is supposed to be the 

 normal food-plant, and the one from which the species 

 takes its name. I then changed the food, giving the 

 remaining three larvfe leaves of the common poplar, on 

 which they fed readily. By June 4th the total number 

 of larva3 which had emerged was sixteen, and no more 

 were hatched. One more larva died, and one was lost 

 in changing the food ; so that the total number remaining 

 for purposes of experiment was ten. 



On June 13th, I divided the larvae into two sets, 

 placing five in cylinder 2 and five in cylinder 6. Those 

 in cylinder 6 were supplied with very young shoots of 

 poplar, in which the stems and the leaves were alike 

 bright green, and no sticks. Those in cylinder 2 were 

 given older twigs, in which the stem was brownish and 

 the leaves much darker green, and perfectly black sticks 

 (the same as those used in previous experiments) were 

 mixed with the food-plant. The larvae were divided as 

 nearly as possible according to age. 



llie larvce witlt dark surroundings. 



Cylinder 2 — June 13th. — I placed five larvae in the 

 first stage in cylinder 2 with black sticks. The first 

 ecdysis occurred. When first hatched the larvae were of 

 a uniform dusky colour ; after the first ecdysis they 

 became very light green, which darkened gradually to 

 almost brown. (This brownish hue did not alter, except 

 in shade, in these larvae after the second ecdysis ; and in 

 this, as will be seen, they differed from the larvae with 

 green surroundings. I considered that the colour-change 

 began, therefore, at this period, unlike li. cratcegata and 

 most of C. nupta, in which it was perceptible only after 

 the second ecdysis.) 



