August, 1880.] 49 



SOME FACTS m THE LIFE-HISTOKY OF GASTHOPHYSA RAPHANI. 



BY J. A. OSBORNE, M.D. 



Having hibernated in the perfect state, underground, as I believe, 

 the beetles of Gastrophysa raphani reappear in spring with the first 

 warm weather at the end of March or beginning of April. At their 

 earliest resurrection, still sexually immature, male and female are un- 

 distinguishable, except as larger size and earlier appearance afford a 

 presumption in favour of the latter sex. Very soon, however, begins 

 that enlargement of the abdomen in the $ , due to the development 

 of the ovaries, and the formation of eggs in them, from which the 

 genus takes its name, and which, to save circumlocution in speaking 

 of it again, may be conveniently designated by the term gastrophysm. 

 Until gastrophysm has been, to some extent at least, developed, I 

 believe there is no fertile union of the sexes. No eggs are laid until 

 it has reached its full extent, when all the abdominal spiracles (four 

 on each side) are completely uncovered, the elytra are tilted upwards 

 reaching only to the middle of the high convexity of the abdomen, 

 and even somewhat separated at the extremities. In the recently 

 excluded imago, on the other hand, the dorsal and ventral segments 

 of the abdomen are connected by a broad wing-like fold of skin along 

 either side, in the angle of which the spiracles are seen looking directly 

 upwards. 



These insects eat, both in the larva and imago states, the various 

 common species of dock and sorrel. The eggs are laid on the under- 

 side of the leaf, only rarely, and, as it were, accidentally, on the 

 upper. The batch consists usually of 40 — 50 eggs ; and I have counted 

 as many as nineteen batches on the under-side of a single leaf, and 

 seen others with, I am sure, many more. The same £ will lay again 

 perhaps in less than 48 hours, and will continue laying for some weeks. 



The ovipositor is telescopic-tubular. It consists of (at least) two 

 pieces. The outer tube, which is exserted first between the semi- 

 circular valves of the pygidium, and remains exserted during oviposi- 

 tion, is bilabiate, having an upper and lower emarginate lip, vhich 

 open by lateral angles. They are strengthened, especially the upper 

 lip, by lateral, crescentic, chitmous thickenings, of darker colour, whose 

 sharply defined convexity is towards the extremity of the lip, shading 

 off less definitely forwards into the substance of the yellowish trans- 

 parent tube. The upper lip, like the upper valve of the pygidium, 

 has also a whitish dilation. Shining through this upper lip, with its 

 crescentic clouds, may be seen two black incrassate-linear appendages, 



