238 THE entomologist's record. 



in one side of a silk-covered cage, and on the other side, separated only 

 by a fine silken screen, a few H. euphorbiae <? s and T. vespertilio ?.s. 

 Of the former, two euphorbiae ? s paired at once with vespertilio ^ s, 

 and subsequently laid respectively 108 and 97 eggs. No pairing, 

 however, took place between vespertilio 2 s and euphorbiae $ s. The 

 eggs all hatched, and the larvae at first did well, feeding hungrily on 

 Euphorbia, and continued to do so up to the final stage. Each stage 

 was carefully drawn and painted for future reference. The following 

 is a rough outline of the various stages of the hybrid compared with 

 those of the parents, a number of each of which were reared side by 

 side with it : — 



First stage. — Vespertilio : Ground colour light yellow, head of the 

 same colour, anal segment rather darker. The setae are exactly the 

 same in the three different larvfe. No caudal horn. 



First sta&e. — FJuphorbiae : Ground colour light olive-green, head 

 and base of prolegs being of a very dark olive-brown colour. Caudal 

 horn from O'Smm. to 0*6mm. in length. 



First stage. — Deusoi: Ground colour light yellowish-green, head 

 rather darker, with a little intermixture of olive. Caudal horn from 

 0-2mm. to 0-3mm. long. Anal segments and prolegs darkish green. 



Second stage. — Densoi differs from euphorbiae in that the yellow- 

 grey subdorsal line is very much more clearly indicated, and the 

 white spots are prominent. The ground colour is nearer that of 

 vespertilio at same stage. The shield on the head is black, and the 

 prolegs vary from green, as in vespertilio, to black, as in euphorbiae. 

 The stigmatal line is more distinctly marked than in euphorbiae, 

 less so than in vespertilio. The caudal horn is short and stumpy, 

 relatively the same length as in the first stage, exceptionally, in a very 

 few cases, it is completely missing (in not one case was it wanting in 

 the first stage). 



Third and final stages. — Densoi varies in the adult larva very 

 much more than in the first two stages, but is altogether within the 

 broad limits of the euphorbiae larvae, from which, however, it differs 

 with regard to the length of the caudal horn. In no case was this 

 horn more than one-half the size of the caudal horn of euphorbiae, and, in 

 several cases, it did not exist at all. In the course of the last stage the 

 larvse were attacked by the fatal " flacherie," and, in spite of every 

 care, 90 per cent, perished. 



Pup^. — These are rather nearer vespertilio than euphorbiae in size 

 and general appearance ; the black markings (almost non-existent in 

 vespertilio) are clearly defined, though not so dark as in euphorbiae. 



Imago. — Two $ and two 5 moths have emerged after three Aveeks 

 of pupal life. The females are full of eggs. The ground colour of 

 the forewing is of the vespertilio-grey, with, in two cases, a yellowish- 

 pink shading combining with the grey; the bands exist as in euphorbiae, 

 but greatly diminished in breadth and in length. The hindwing is the 

 hindwing of vespertilio, but with a broader pink outer margin. The 

 underside is much pinker than in vespertilio, which it resembles with 

 regard to the grey marginal bands of the hindwing. The abdomen 

 and thorax strongly resemble those of euphorbiae. However, in two 

 insects, the 3rd abdominal black band is visible as in vespertilio. 



As noted above, this new hybrid has been carefully drawn and 

 coloured at every stage, side by side with the parent larvfe and pupae, 



