INSKCTA. 



867 



Fig. 348. 



Fig. 349. 



Deilephila elpenor, the Elephant Sphinx. 



or in a cell of the earth. The perfect insects 

 fly very swiftly, and are mostly abroad at 

 twilight. 



In the third section, Pomeridiana, which 

 includes the silkworm-moths, the body is short 

 and thick, proboscis in general very short, 

 antennae tapering, and much pectinated or 

 feathered in the males, and the wings, when at 

 rest, deflexed and horizontal. The larva before 

 changing incloses itself in a case, which in the 

 T$ombycid(E is composed entirely of fine silk. 



In the fourth section, Nocturna, night-moths, 

 the antennae are setaceous, the proboscis long 

 and spirally convoluted, the palpi compressed 

 and terminated abruptly by a minute joint, and 

 the wings, when at rest, folded horizontally upon 

 the abdomen. It is a larva of this section, 

 Agrotis segetum, that of late years has been 

 almost as injurious to the agriculturist by attack- 

 ing the full-grown turnip as that of the saw- 

 fly, Athalia, or the beetle, Haltica, by attack- 

 ing the plant in the earliest stages of its growth. 



In the fifth section, Semidiurna, the body is 

 slender, the antennas in general setaceous, the 

 proboscis short, and the wings broad and ex- 

 panded horizontally, as in the Geometridte, or 

 deflexed and forming an angle with the body as 

 in the Pyralidte. 



The sixth section, Vespertina, is composed 

 of minute species, among which are the de- 

 structive clothes-moths, Tineida. 



Order IX. DIPTERA. 



Wings two, membranous, naked, and si- 

 tuated anteriorly to two minute pedunculated 

 bodies (halteres), the analogues of the pos- 

 terior wings in the preceding orders ; * meso- 

 ihorax very large, and forming nearly the whole 

 of the thoracic region ; head rounded, distinct 

 from the thorax ; mouth rostriform ; metamor- 

 phosis complete ; pupa coarctate. 



Among the families of this extensive order 

 are the Cuticu&r, gnats, the Asilid<e (Jig. 349) 

 and Tabanida, bloodsuckers, the (Estrida, 

 gad-flies, and Muscida, common house-flies. 

 In most of the families the larvae are active and 



* Kiiby and Spence, Introduction, &c., vol. ii. 

 p. 354. 



Asilus crabroniformis (Samouelle). 



apodal, or are furnished only with abdominal 

 feet. It is doubtful whether any of them cast 

 their skins during their growth. In most species 

 it becomes the outer covering of the pupa. 



Order X. HOMALOPTERA. 



Wings two, or entirely absent ; head sunk 

 into the anterior part of the thorax, or divided 

 from it only by a suture ; abdomen flat, broad, 

 and obtuse ; anus notched ; claws large, biden- 

 tate or tridentate ; metamorphosis complete : 

 pupa coarctate. 



In this remarkable order, the forest-flies (fig. 

 350) and ticks, the larva is nourished, and un- 



Fig. 350. 



Hippobosca eqiuna, the Forest-fly (Samouelle). 



dergoes its change into the pupa state within the 

 abdomen of the parent, as was first noticed by 

 Reaumur, by whom they were designated " spi- 

 der-flies." Soon after the pupa is deposited, it 

 becomes greatly enlarged, and equals in size the 

 body of the parent. Reaumur found that its 

 outer envelope or case is formed of the skin of 

 the larva, as in the true Diptera, and he also 

 succeeded in detecting within it the proper 

 covering of the nymph. The type of the order, 

 the forest-fly (fig. 350) is exceedingly trouble- 

 some to horses in the summer, and abounds in 

 the New Forest in Hampshire. 



Order XI. APHANIPTERA. 



Wings none ; body oval, compressed ; head 

 small, rounded, and compressed ; eyes simple, 

 orbicular; thighs strong; posterior legs the 

 longest ; tarsi five-jointed. 



The Pulicidtfy fleas, undergo a complete 

 metamorphosis. The larva is an active elon- 

 gated worm, which spins itself a case or coc- 

 coon, in which it becomes a nymph, and at 

 the end of a few days assumes the perfect 

 state. One species, Pulex penetrans, is ex- 

 ceedingly troublesome in the West Indies by 

 introducing itself beneath the toe-nails or under 

 the skin, where it occasions malignant ulcers. 

 Most of the species are of diminutive size, and 

 seldom exceed a line in length. Mr. Kirby, 

 3 L 2 



