418 NATURAL HISTORY OF ARTHROPODS. 



the world. They are usually of moderate size, and sluggish in their habits, being 

 easily caught ; the larger species are commonly found in meadow or woodlands, rest- 

 ing upon stems or trunks of trees, with their heads downwards. They are some- 

 times predaceous upon other insects. 



The larvae are cylindrical, with or without fleshy abdominal legs, sometimes bristly ; 

 the last segment has a transverse cleft, the upper portion of which is provided with 

 two, often backward-bent processes. The pupsB are free as usual ; are not provided 

 with spiny tubercles on their front end, and the posterior end has two points below 

 and four above. The abdominal segments have above, or entirely around, a row of 

 bristles. The larvse are predaceous, living either in the earth, in decaying wood, or 

 in the passages made by beetles ; others live in moss, in dry sand, or in water. The 

 eggs of Atherix are deposited in large pear-shaped masses attached to dried branches 

 overhanging water. Not only do numerous females contribute to the formation of 

 these clusters, but they remain there themselves and die ; the newly hatched larvse 

 escape into the water. The adults of the genus Vennilio deposit their eggs in the 

 sand, and the larvffi form conical pitfalls in which to ensnare small insects in the man- 

 ner that the ant-lion does. The tenth segment bears above at its tip a transverse 

 row of long booklets directed backward, but with the hooks bent forward ; the eleventh 

 segment has a similar row directed forward, the hooks of which are bent backward. On 

 the fifth segment below there is a single unpaired grasping foot which is capable of 

 being protruded forward and downward ; at its tip there are two triangular, sharp, 

 flat chitinous spots, and below them some stiff bristles. The booklets serve as aids in 

 boring in the sand and to fix themselves ; the organ on the fifth segment enables the 

 larva to seize and hold the prey ; so securely, indeed, are such insects as ants grasped 

 behind their necks, that they cannot bite ! This last organ also serves, through a 

 lateral motion of the front end of the body, to cast out a quantity of sand in the 

 process of forming their conical pitfalls. 



The family MiDASiDiE, though a small one, including but one hundred known 

 species, is composed chiefly of large, often very large, flies. They will be recog- 

 nized best by their antennaj, which are elongated and clavate at their tip, the third 

 joint composed of several distinct segments ; the veins of the wings are complicated 

 and variable. The earlier stages are known in but two or three species. The larvae 

 of Midas fulvipes are known to live in decaying sycamore trees and are probably car- 

 nivorous in their habits. They are from one and a half to nearly two inches in length, 

 cylindrical, and with swellings below the abdominal segments for locomotion. The 

 pupa of M. davatus has at its anterior end, eight strong, sharp booklets. The hind 

 edges of the abdominal segments are provided' with a circlet of flat, three-cornered 

 thorns which are directed backward. On the tip of the last segment there is a pair 

 of strong claw-like hooks bent downward. The fly is of a deep black color with an 

 orange-colored band across the base of the abdomen above ; they are found about old 

 stumps and logs in the latter part of June and July. Other species are said to be pre- 

 daceous in the larval state upon Prionus and other beetles. 



The AsiLiD^ or Robber-flies, as the Germans call them, comprise a large family 

 scattered over the world and numbering about twenty-five hundred known species. 

 They are mostly large, some very large, one species from the West measuring two 

 inches in length. The three basal cells of the wing are much prolonged ; the third 

 longitudinal vein is furcate, and there are five posterior cells. The third joint of the 

 antennae is simple, and the under lip is horny ; there are also two fleshy pulvilli on 



