HARDWICKE'S SCIENCE-GOSSIP. 



NOTES ON "GONOPTERYX RHAMNI.' 



By R. D. POSTANS. 



JHEN at Heidel- 

 berg last summer 

 I found a con- 

 siderable number 

 of the larva: of 

 G. Rhamni, and 

 had an oppor- 

 tunity — which I 

 had never before 

 had — of watching 

 the growth of the 

 caterpillar almost 

 from the egg up 

 to the time of its 

 passing into the 

 pupa stage. Per- 

 haps a few notes 

 on these cater- 

 pillars may be 

 acceptable. 



Observing the food plant (Rhamnus frangula) one 

 day during a ramble on the hills above Neunheim, I 

 noticed that one or two leaves had been eaten, and 

 after a very short search I found a caterpillar ; in colour 

 of a dull lightish green with a whitish mark down each 

 side. It had placed itself on the upper surface of a 

 leaf, at about the centre ; the after part of its body 

 was parallel to the surface of the leaf, but the anterior 

 portion was elevated at an angle of about 20°. 



I found this was invariably the position of the 

 caterpillar when not eating, and that when so at 

 rest the hinder feet were attached to a sort of web 

 spun on the surface of the leaf, to afford, I suppose, a 

 more secure footing. 



The first day I searched I found about fifty speci- 

 mens. I picked a small twig with each caterpillar 

 (not attempting to remove any from the leaves they 

 were on) and carried home the twigs in a bunch, not 

 being especially careful about shaking them, and I 

 did not lose one. 



I put the twigs, just as they were, in a jug of water, 

 and placed this just outside the window without 

 covering them in any way. 

 No. 268.— ArRiL 1887. 



The caterpillars never attempted to crawl away, 

 and only moved to eat, which was for the most part 

 done at night. 



Every few days I had, of course, to give them fresh 

 food, when I moved them with a feather from the old 

 leaf to a new one. It was in doing this that I satisfied 

 myself as to the web spinning above referred to. 



Just before going into the pupa state each larva 

 became almost translucent, so that I could always 

 tell when that stage was imminent. 



The caterpillar would then suspend itself either on 

 the under surface of a leaf or — and this was a very 

 favourite place — under the top of the handle of the 



J u g- 



They passed into the chrysalis state in a very few- 

 hours after suspension, and for a day or two looked 

 like chrysalis cases filled with a light greenish fluid, 

 They however gradually became more opaque, and' 

 in about a fortnight the wings (of the male, bright 

 yellow) were distinctly discernible, a sign that the 

 imago would very shortly emerge. 



Apparently at Heidelberg G. Rhamni is not 

 troubled by the ichneumon, as though I bred some 

 dozens I had not any so affected, but somehow or 

 other there must be a great slaughter of the larvae, for. 

 when I made a careful search for the pupre, which I. 

 did when my own began to hatch out, I could not 

 — though I devoted a whole day to the search — find a 

 single specimen. I should add that the caterpillar is 

 solitary, though three or four specimens may some- 

 times be found on the same plant ; and that, as a 

 rule, it is a night-feeder. 



Rhamnus frangula is very abundant as a small 

 diffuse-growing bush on some parts of the hills above 

 Neunheim. 



St. Lconards-on-Sca. 



"Professor Haeckel is gone to the East" — (a 

 rather indefinite geographical place for an accurate 

 scientific Journal to localise). But we copy from a 

 weekly contemporary that has never ye.t proved itself 

 wrong ! 



