162 NATURAL HISTORY OF ARTHROPODS. 



such legs. It should be observed, however, that the abdominal legs in the larval 

 Panorpa are quite small and rudimentary. 



Moreover, as in caterpillars, there is a large pair of spiracles on the prothoracic 

 segment, but none on the second or third segments ; while the fourth to eleventh, be- 

 hind the head, each have a pair of spiracles. This arrangement of the spiracles, or 

 breathing pores, is identical with that of caterpillars. The head is rounded, and not 

 very large. On the whole, as Brauer observes, " the form of the larva is caterpillar- 

 like." In confinement the larva digs a horseshoe-shaped passage, an inch deep, in damp 

 earth, and lives on putrid meat and bread. Brauer also found one larva in a deep 

 mouse's nest, situated between decaying roots ; another under a stone, in a damp, 

 though nearly dry, forest brook ; and a third time, one was found under a moss-grown, 

 mouldering stump, with ants, not feeding on them, but rather sharing with them their 

 food, dead animals. In order to pupate, the larva makes an oval cavity in a lump 

 of earth, and buries itself deep in the ground. As a rule the larva? are sluggish, but 

 can, if pursued, creep rapidly. The larva? remain in their holes from ten days to three 

 weeks before casting the larval skin, and after remaining in the pupa state fourteen 

 days transform into the final, or imago state. 



The life-history of Bittacus possesses similar interest. This insect is like Panorpa, 

 but the male has no forceps, and in form, with its slender body and long legs, strik- 

 ingly resembles a Tipula, or daddy-long-legs fly, except that it has four instead of two 

 wings. The imagines, or adult flies, live in a sort of chamber, covered in by leaves, 

 grasses, nettles, etc., forming an airy abode, or vivarium. Here they feed on such flies 

 as enter their habitation. The flies die after laying their eggs in the soil and the earth 

 at the bottom of the chamber dries up, but in the following April, when the soil is 

 again wet by the spring rains, the larva? hatch out. And now a remarkable fact has 

 been noticed by Brauer. He has observed that if the marshy or wet ground, where 

 the female Bittaci customarily lay their eggs, does not dry up, no females appear until 

 the second year following ; so that the eggs lie over unhatched two years. The first 

 condition of their hatching is a complete drying of the earth in which the eggs lie; 

 the second condition is a succeeding thorough wetting of the ground in spring. If the 

 ground remains dry from want of snow in the winter, or of rain in the spring, and there 

 follows in the next summer a very thorough wetting of the soil, then the time of appear- 

 ance of the adult will be retarded three or four months. This is quite analogous to 

 the case of the eggs of Phyllopod Crustacea, which will remain unhatched for several 

 years if deposited in mud which becomes dry. 



The larva of Bittacus, unlike those of Panorpa. and Boreas, does not bore into the 

 earth, but lives on top of the ground under leaves, or remains secreted under a clod ; 

 in confinement it will live for several weeks if fed with raw meat. 



The larva? have, like those of Panorpa, a remarkable resemblance to caterpillars, 

 especially certain silk-worms, or caterpillars of butterflies, as well as to saw-fly larva?, 

 such as certain species of Selandria. Unlike the young of Panorpa, the larva of 

 Bittacus is protected by two rows of dorsal spiny tubercles which end in long stiff 

 filaments, and which extend from behind the head to the tail. They also have, besides 

 the six thoracic legs, a pair of small two-jointed prop-legs on each abdominal segment, 

 or eight pairs in all, and are thus like the larva? of certain saw-flies (Lophyrus). From 

 their reddish-gray color, and the resemblance of the hairs on their back to particles of 

 earth and bits of plants, they are hard to detect, and are thus easily overlooked by 

 birds and other enemies, Moreover, at the least disturbance they assume an erect 



