VIII. B, 3 Mitzmain: Biology of Tabanus striatus Fabricus 211 



The palpi and antennae in this species are silvery white, and 

 usually found glistening with moisture. 



The eyes are oval in shape, with the long axes parallel. When 

 the larva is prepared to molt, the pigmented spots are usually 

 distorted. In this species the eye spots or ocelli are very prom- 

 inent, especially in the younger stages of the larva. They can 

 be first seen in the embryo where they appear as dark beaded 

 structures through the chorion of the well-developed egg. In 

 the young stage of the larva the eyes appear in the pharyngeal 

 cavity midway between the mouth and the cephalopharynx, and 

 as growth continues they are located nearer the distal end of the 

 head capsule ; so that when the larva is full-grown and the mouth 

 structures protrude in locomotion or prehension the eye spots 

 are seen to project on the head capsule with the mouth parts. 



The trachea which terminates in the conical tubular siphon is 

 lead gray in contrast to the dense white of that portion anterior 

 to the anal segment. Anterior to the siphon there is a cuticular 

 collar of a slightly darker shade. 



The prolegs are formed by truncated projections, 6 in number, 

 3 on each side of the midventral line and extending laterally. 

 Each protuberance is provided with a tuft of short, fine, brown 

 hairs. These hairs appear to be surrounded by a secretory sub- 

 stance, which is slimy in character. 



At the base of the siphon, beneath the cuticle on the dorsal 

 side opposite the anal capsule, is a tiny structure which attracts 

 attention on account of its movements and peculiar arrangement. 

 In the newly hatched larva it is a process composed of 4 lustrous 

 black disks arranged in two pairs, one in front of the other, and 

 set in a mass of fat bodies. The larger of the disks, the anterior 

 pair, is less than 0.1 millimeter in diameter. The movement 

 of the process is similar to that of a pendulum, and is active 

 only when the larva moves. With each molt these disks become 

 smaller and increase in number. In the full-grown larva the 

 process becomes a triangular mass of loosely arranged beaded 

 disks. They appear to be mere specks of pigment beneath the 

 skin, but their structure and action are so constant that either 

 the process is characteristic of the species or investigators have 

 overlooked or ignored them in other species. 



DESCRIPTION OP THE PUPARIUM 



The average length is 18 millimeters, and width, 3.5 milli- 

 meters. The color is pale brown, the last 2 segments of the 

 abdomen being slightly darker. The head tubercles are not 



