144 ENTOMOLOGY 



wet cloth, without consistency and firmness, and as yet entirely unfit for 

 flight, but after one or two hours they become sufficiently stiff, assuming 

 the beautiful form characteristic of the species." (Trouvelot.) The 

 expansion of the wing is due to blood-pressure brought about chiefly by 

 the abdominal muscles. In the freshly-emerged insect, the two mem- 

 branes of the wing are corrugated, and expansion consists in the flattening 

 out of these folds. The wing is a sac, which would tend to enlarge into 

 a balloon-shaped bag, were it not for hypodermal fibers which hold the 

 wing-membranes closely together (Mayer). Samia cecropia also uses 

 a dissolvent fluid ; Tropcea luna, Philosamia cynthia and others cut and 

 force an opening through the cocoon by means of a pair of saw-like organs, 

 one at the base of each front wing. 



Hypermetamorphosis. In a few remarkable instances, metamor- 

 phosis involves more than three stages, owing to the existence of super- 

 numerary larval forms. This phenomenon of hypermetamorphosis occurs 

 notably in the coleopterous genera Meloe, Epicauta, Sitaris, Rhipiphorus 

 and Stylops, in male Coccidas and several parasitic Hymenoptera. 



In Meloe, as described by Riley, the newly-hatched larva (triungulin} 

 form) is active and campodea-form. It climbs upon a flower and thence 

 upon the body of a bee (Anthophord), which carries it to the nest, where 

 it eats the egg of the bee. After a moult, the larva though still six- 

 legged, has become cylindrical, fleshy and less active, resembling a lamel- 

 licorn larva; it now appropriates the honey of the bee. With plenty 

 of rich food at hand the larva becomes sluggish, and after another moult 

 appears as a pseudo-pupa, with functionless mouth parts and atrophied 

 legs. From this pseudo-pupa emerges a third larval form, of the pure 

 cruciform type, fat and apodous like the bee-larvae themselves. After 

 these four distinct stages the larva becomes a pupa and then a beetle. 



Epicauta, another meloid, has a similar history. The triungulin 

 (Fig. 218, A) of E. vittata burrows into an egg-pod of Mclanoplus differen- 

 tiates and eats the eggs of that grasshopper. After a moult the second 

 larva (carabidoid form) appears; this (B) is soft, with reduced legs and 

 mouth parts and less active than the triungulin. A second moult and 

 the scarabceidoid form of the second larva is assumed; the legs and 

 mouth parts are now rudimentary and the body more compact than 

 before. A third and a fourth moult occur with little change in the form 

 of the second larva, which is now in its ultimate stage (C). After the 

 fifth moult, however, the coat elate larva, or pseudo-pupa, appears; this 

 (D) hibernates and in spring sheds its skin and becomes the third larva, 

 which soon transforms to a true pupa (E), from which the beetle (F) 



