THERETRA PORCELLUS. 95 



on a piece of damp rag and kept in a metal glass-topped box, 

 and observes that a batch of ova, not so treated, although 

 developing well until the final stage, failed to produce their 

 larvae, whilst of another batch, placed on the damp rag, 98 out 

 of 110 hatched, and none of the 12 failures contained a larva. 

 Holland notes that the eggs are usually laid 2 or 3 together. 



Ovum. — Small (for a Sphingid egg), oval (some approaching 

 circular) in outline, the upper surface much indented, a circular 

 depression occupying the greater part of the top ; the surface ot 

 the egg is covered with a faint polygonal reticulation, and the 

 egg has the appearance of being spotted all over with small, 

 whitish, deep-seated pits, colour bright pea-green [Described 

 July 10th, 1 90 1, from eggs received from Mr. Head]. As the 

 egg gets older the colour becomes pale greenish-yellow, and 

 the embryo is very distinctly seen inside, the black tubercular 

 setae being seen very clearly through the eggshell (Tutt). Smooth, 

 rounded, oval in outline, a deep depression on the upper (un- 

 attached) side; i'2mm. long, i^mm. wide, and rather less in 

 thickness ; colour vivid green, surface covered with a faint and 

 irregular cell reticulation, the walls consisting of a raised net- 

 work, enclosing depressed areas, the walls broad but exceedingly 

 low ; nothing definite can be made out of the structure of the 

 micropyle [Bacot, June, 1901. Eggs about to hatch ; received 

 from Mr. W. Barnes]. Very broad, oval in form, 1.2mm. long, 

 imm. wide; the shell thin and shiny, colour light green (Hellins). 

 Light green in colour, spheroidal in form, very similar to those of 

 Eumorpha elpenoi- (Weismann). Bartel describes the egg as " oblong- 

 oval, greenish, covered on upperside with many black dots " ; 

 these black dots are evidently the tubercles of the embryo showing 

 through the transparent shell. 



Habits of larva. — The newly-hatched larva eats a considerable 

 portion of the eggshell, at least one-third, it never seems to eat the 

 whole. As soon as it settles down on its food it rests on the 

 underside of the leaf which is, in the case of Galium verum, just 

 wide enough to hide it from above (Bacot, June, 1901). The newly- 

 hatched larvae seemed at first to like the flowers of Galium verum, 

 but very soon altered their taste and showed a preference for the 

 leaves, apparently not caring to touch the flowers when a fresh supply 

 of food was given to them. Some that hatched July 20th, 1886, 

 moulted four times, viz., July 25th, July 31st, August 6th, and August 

 nth (Hellins). The larva lives at the same time as, but rarely 

 in company with, that of E. elpenor, the larva affecting rather 

 meadows and sunny slopes than ditches, and preferring dry localities, 

 whilst that of E. elpenor is found chiefly in damp situations (Bartel). 

 The fullgrown larvae may be sought at the end of July on the 

 various species of Galium, from 8 p.m. to midnight, with a lantern, 

 the larvae being often thus found in large numbers. In some years 

 they are (with the larvae of Sesia stellatarum) very abundant on 

 the stunted plants of Galium growing on the Kent coast from 

 Deal to Dover, but are difficult to find during the day. Some 

 30 — 40 larvae were taken in the autumn of 1872 with a lamp after 

 dark at Painswick (Watkins), on the sandhills between Waterloo 

 and Formby, and between New Brighton and West Kirby, also 



