422 MODERN CLASSIFICATION OF INSECTS. 



black, but soon assumed a darker colour. The insect changes its skin 

 six times before arriving at perfection. Three of the specimens, care- 

 fully observed, offered the following periods of the various moults: — 



Thus making seven weeks' difference in the arrival at the perfect state, 

 although the insects were from the same capsule, all females, and all 

 subjected to the same treatment. At the third moult the meso- 

 and meta-thorax had increased in size, and still more visibly after the 

 fourth; after the fifth the insect is in the pupa state: the prothorax has 

 attained its full size during this period. " Peu-a-peu les fourreaux des 

 ailes (les deux anneaux susmentionncs) se separent et s'etendent." 

 (^Hummel, Op. Cit. p. 9.) In a communication published in the Field 

 Naturalist, p. 129., it is stated that, during the time of moulting, the 

 insect is assisted in disengaging itself from its old skin by its com- 

 panions. The larvaa of Blatta are moderately long, flattened, and 

 narrowed in front {Jig. 51. 18.) ; those of Polyphaga are short, convex, 

 and nearly hemispherical ; with the legs short, and the tibia; slender 

 and armed with strong spines. The larva; of the Blaberi resemble the 

 Molluscous Oscabrions, being of an oval and rounded form, very 

 < onvex, with a broad margin ; those of Panesthia have the surface of 

 the thorax irregular, as in the perfect insect. Generally, the larvae are 

 ornamented with spots of red or buff, which disappear on their arrival 

 at the perfect state. 



These insects are subject to the attacks of various parasites. In the 

 Isle of Bourbon, a species of Sphex provisions its nest with the Bl. ame- 

 ricana, which it wounds with its sting, so as to render it immovable, and 

 then deposits in the nest it had prepared, and upon which its future 

 progeny subsist. The species of the genus Evania also appear to be 

 attached to these insects ; Kirby and Spence stating, on the authority 

 of Dr. Arnold, that they are parasitic upon them. Mr. MacLeay, how- 

 ever, informs me that it is upon the capsule of eggs that the Evania sub- 

 sists. Evania minuta is found upon Parley Heath, Dorset, where Blatta 



