FLIES. 415 



tion generally consist of transverse swellings on the under side which are pro- 

 vided with very minute bristles. The terminal end of the body is truncate, and the 

 single pair of spiracles are situated here, in which character these larva? diff er from 

 those of allied families. On the borders of this truncation there are four or five 

 retractile fleshy processes. 



Most of the larvad live in the earth, or in soil-like, decomposing wood ; some, how- 

 ever, live in water, and are soft and slimy, of a dirty, greenish color, and clothed with 

 short, appressed, microscopic hairs. Still others live on leaves of plants, almost like a 

 caterpillar in appearance, in some the resemblance still more heightened by being 

 green in color and provided with a crest of tubercles along the back. 



The pupae, like most of those in this sub-order, are free. The thorax has two 

 stigmatic tubes, and one of them, as in Ptychoptera, may acquire a very great length 

 for the piirpose of breathing under water. The abdominal segments of the pupaa 

 have transverse rows of hairs, bristles, or spines, which enable them to extricate 

 themselves when about to complete their metamorphoses. 



The adult flies are not often seen early in the season, but more commonly in the 

 late summer and autumn. They will be most usually met with in meadow lands and 

 forests, flying awkwardly for a few steps close to the ground till they become 

 entangled in the grass or twigs, and then, extricating themselves, rise again to repeat 

 the same aimless, clumsy flight. A singular species, Bittacomorpha clavipes, found 

 throughout North and South America, is seen both in early spring and late in the 

 autumn, and will strike the observer as ludicrous in appearance. The legs are very 

 elongate, variegated in color and thickly clubbed at their tips. They fly very slowly, 

 with their legs extended, and one is lucky if ; in attempting to capture a specimen, 

 he succeeds without the loss of half of them. One cannot readily understand why 

 the legs are so delicately attached in this and the allied families. It is probably to 

 enable the fly to escape the entanglements that these apparently useless members are 

 constantly subjecting them to, thereby often saving their lives, at least long enough to 

 reproduce their young. That the loss of several legs does not seriously affect them 

 is evident from the fact that a mosquito will continue pertinaciously to seek its food 

 when one, two, or even three are missing ! 



Very noticeable species are several of Trichocera, so small and deli- 

 cate that singly they would hardly attract our attention, but they collect 

 in large numbers, forming a small cloud that may often be seen dancing 

 up and down at twilight, in late autumn and early spring, as well as 

 on the more pleasant days throughout the winter. 



The name of ' Daddy-long-legs ' is the one most usually applied 

 to members of this family in England, but in America this term is 

 commonly used to designate the Phalangidas or harvest spiders. The 

 English name of ' Crane-flies ' is preferable. Commonly they are FIG - 

 harmless, but some of the species in the larval state are very destruc- 

 tive, feeding upon the tender rootlets of 



(j T^-y^^ grass and grain, and causing the plants over 

 /I - JLJf | j~\ large surfaces to wither and die. There 



FIG. 521. - Larva of Chionea. are twelve hundred species known. 



In this family are placed several wing- 

 less forms, or those with the wings more or less rudimentary. One of the former is 

 Chionea, the species of which are found on snow, the larvae living in vegetable matter. 



