130 THE ENTOMOLOGIST. 



and Taschenberg ; it is certainly British, being commonl}^ bred 

 from Smeriuthus ocellatus. 



The talented George Newport made Trogus lutorius the 

 subject of one of his numerous anatomical studies, and the 

 results are given in an important memoir communicated to the 

 Linnean Society in June, 1849 (Trans. Linn. Soc, xxi., pp. 85 — 

 'J3, pi. ix. ; 1853). The following is the economy of Trogus as 

 observed by Newport. The egg is laid in the Sphinx-larva, 

 probably directly after it changes its skin for the last time, since 

 Newport found the parasitic larva more than one quarter of an 

 inch in length about a week before the caterpillar was full fed ; 

 the Ichneumon larva was always " internal to the muscles, 

 imbedded in the so-called fatty tissue, between them and the 

 alimentary canal, and always on the dorsal surface, and usually 

 with its head in the direction of that of the caterpillar. I have 

 found it in different stages of growth, from one-fourth to three- 

 eighths of an inch in length, as early as the middle of August, when 

 it is of a light pea-green colour ; but I have obtained full-grown 

 specimens only from the pupa of the Sphinx, sometimes as early 

 as the end of October, but more frequently not until the 

 commencement of March, and sometimes as late as the end of 

 Aj)ril. Usually one egg only is deposited in each caterpillar, but 

 sometimes there are two, and both become hatched, although of 

 the parasites one only arrives at maturity, as one is invariably 

 destroyed by the other." One case (March 13th, 1832) is fully 

 recorded, and this apparently was by no means a unique one. 

 " The usual situation of the parasite in the Sphinx-pupa is in the 

 tissue of the middle part of the body beneath the dorsal vessel 



and above the stomach, on which it often rests The change 



to a nymph usually takes place in April, but when placed in water 

 at that period it soon perishes, as its respiration has then become 



more active The length of time which it remains in the 



nymph-state is about a month or six weeks at the utmost, as most 

 of the specimens I have bred from the pupa have appeared in 

 June. The perfect insect makes its way out of the dead pupa of 

 the Sphinx by perforating the case with its mandibles on the 

 dorsal surface, and sometimes it becomes fixed in the orifice and 

 unable to escape." The larva is described in full detail. This 

 life-history may be taken as typical of the Ichneumonidce 

 generally ; compare the remai^ks under Ichneumon. 



