THE GENUS SMEEINTHUS. 173 



I'iie Qenus guiepinthus.* 



By A. BACOT. 



There are only five European representatives of the genus 

 Smerinfhiis — tih'ae, oreJldfns, popnli, qucreus and tremulne — only the 

 first three of which are found in the British Islands. S. qucrcus is a 

 rare species, occurring in Southern Europe and Asia Minor. S. tremulae 

 is very rare, and is confined to Central and Nortliern Europe ; it seems 

 doubtful whether it is specifically distinct from S. popnli. Some papers 

 by Mr. E. B. Poulton on the larva? {Tram. Eat. Soc. Loud., 1884:- 1888) 

 led nie to try and breed our three indigenous species from the egg, 

 and this paper is based on the notes which I made in the coui'se of my 

 experiments. 



The Eggs. — There is great similarity in colour between the eggs of 

 the three species. Those of S. ocellatus and S. populi are bright 

 emerald-green, and have a pearly lustre when fresh ; those of S. tiliae 

 are duller and more of an olive-green ; those of all three have a semi- 

 transparent appeai'ance. The eggs of S. tiliae and S. ocellatus are 

 almost exactly alike in size and shape — a longish oval, about ^/i^ in. 

 in length ; that of S. populi, though not much longer, is rounder, and 

 in bulk is nearly half as large again as either of the others. The 

 surface of the eggs is smooth and shiny, but under the microscope it 

 is seen to be slightly granular in structure. Just before hatching, the 

 eggs are slightly tinged with white. They are usually dejjosited on 

 the underside of leaves, either singly or in pairs. Less frequently 

 those of S. ocellatus and S. populi are found on the smaller twigs and 

 leaf-stalks, but I have never heard of those of S. tiliae being found in 

 a similar situation. Hatching usually takes place in from ten to four- 

 teen days — accoi'ding to temperature. 



The Lakv.e. — The newly-hatched larvfe have certain characteristics 

 common to all three species. They are of a whitish-green colour, the 

 white appearance being caused by a dense growth of short, bristly 

 hairs, which entirely cover the larva, with the exception of the head, 

 scutellum, juncture of the segments, and 13th segment; these hairs 

 are forked at the tip, and look under the microscope as if there were a 

 star on the top of each of tliem. On the head, scutellum and 13th 

 segment there are a few scattered hairs, and a few longer hairs are 

 scattered over the body, but these are not as a rule forked — or only 

 slightly so. The horn is proportionately much longer in the first skin 

 than in any of the later ones ; its tip is bifid, each prong ending in a 

 long bristle which is simple or slightly knobbed at the tip. It is 

 covered, like the body, with short, forked hairs, which are black in 

 S. tiliae and S. ocellatus, green in S. populi. The head, in S. tiliae 

 and S. ocellatus, is round in the first skin ; in S. populi it is roughly 

 triangular. 



After the first moult there is a very noticeable change in the 

 a}){)earance of the larva?. Instead of the dense growth of short hairs 

 which were such a conspicuous feature in the i)receding skin, they are 

 now covered with numerous tall, cone-shaped tubei'cles of a bright 

 yellow colom-, surmounted by insignificant hairs. Although the tubercles 

 are thickly scattered over both body and horn, I do not think they are 



* A pai)er read before the City of London Entoniological and Natural History 

 Society, on March 5th, 1895. 



