HYLES EUPHORBIA. 229 



first ecdysis occurs after five days, and with this there appears 

 quite suddenly a very complicated pattern. The ground-colour is 

 now a light yellowish-green (fig. 39), and, on each of the 12 seg- 

 ments, near the front border, there is a pure white round spot in 

 the middle of a large black transverse spot. These are designated 

 as the white " mirrors " on black " ground-areas," both together 

 constituting " ring-spots," as distinguished from " eye-spots " proper, 

 in which a " nucleus," the pupil of the eye, is also added. In many, 

 but not in all, specimens, very distinct traces of a subdorsal line 

 can be seen as a light whitish stripe connecting the white spots. 

 The horn, the thoracic legs, prolegs, and some spots on the head 

 are black. The larvae remain unaltered till after 4 days, when, 

 having a length of 17 mm., the second moult takes place, bringing 

 with it changes quite as great as those which occurred with the 

 first. Third instar : The larva now assumes the shagreened ap- 

 pearance which it possesses in the adult stage. Small white warts 

 are arranged in rows from the dorsal to the spiracular line, and 

 again, underneath this line, on the abdominal legs. These dots 

 are not only of value as a character for differentiating Deilephilid 

 from Chcerocampid larvae, but they also play a part in the peculiar 

 spot-marking, which will be shown later on. The ground-colour 

 of the larva is now light-green (fig. 40), replaced by black on certain 

 parts. From the black "ground-area" of the ring-spots, two black 

 triangles extend towards the posterior borders of the segments, but 

 usually without reaching them. The ring-spots are not essentially 

 changed, although it may be observed that, in most specimens, 

 the shagreen dots under each ring-spot are somewhat larger and 

 stand closer together than in other places. In the following stage 

 they become fused into a second white " mirror," so that two ring- 

 spots stand one above the other, their black ground-areas meeting. 

 The formation of the second ring-spot sometimes takes place in 

 the present stage (fig. 42). The subdorsal line has now com- 

 pletely vanished, whilst the infraspiracular line appears as a broad 

 stripe above the legs. The horn is yellow with a black point, 

 and the black spots on the head have increased in size. Fourth 

 instar: The third moult, which again occurs after 4 days, is not 

 accompanied by such important changes. The green ground-colour 

 has now completely disappeared, and is replaced by a dull black. 

 The larvae are now, as also in the previous stage, extremely variable. 

 Thus, for example, a triangular patch of the green ground-colour may 

 be retained on the posterior edge of the segments (fig. 41), those 

 specimens which possess this character generally having their mark- 

 ings retarded in development, as shown by the absence of the second 

 "mirror" of the ring-spots. In fig. 41, the shagreen-dots, from which 

 this second mirror is subsequently formed, are distinctly larger than 

 the others, and, on the 1 ith segment, two of them have already 

 coalesced. Fifth instar: After another period of four days, the 

 fourth moult takes place. The marking remains the same, but the 

 colours become more vivid, the brick-red of the head, horn, dorsal 

 line and legs changing into a fiery-red. The infraspiracular line, 

 formerly green alternating with yellow, generally becomes resolved 

 into a row of reddish-yellow spots. Ten days later the larva (8*5cm. 

 in length) ceases to feed and prepares for pupation. In this last stage 



