358 



long and rather slender, the apical joint longer than the basal ; labrum 

 pointed, armed beneath with some strong short bristles ; maxillae stout, 

 their palpi as long as the antennae and stouter, the joints well dif- 

 ferentiated; mandibles long and strong, distinctly curved downward 

 and slightly backward. Thorax sometimes with 8 slightly elevated 

 areas that appear somewhat like plates — a broad one on venter, a 

 similar one on dorsum, and 3 narrow ones on each side. Body with 

 close longitudinal striae; pseudopods distinct, arranged in a circular 

 series on anterior margin of each abdominal segment except the 

 apical one ; apical segment with the spiracular portion retractile, the 

 spiracles in a vertical cleft. 



Pupa. — Similar in general appearance to the pupa of Tahaiuts 

 (PI. LI, Fig. 6), the principal differences between the genera as stated 

 in the key. 



Tahanus Linne 



In point of numbers this genus is the largest of the family, and 

 it also contains the largest species, some of them exceeding an inch 

 in length. 



GENERIC CHARACTERS 



Larva. — The larvae of Tabauus closely resemble those of Clirys- 

 ops in general structure, being elongate, circular in cross-section taper- 

 ing at both extremities, and armed, at least on the abdominal seg- 

 ments, with more or less wTll-defined pseudopod-like tubercles — 2 on 

 dorsum and 4 on venter — which usually form an almost complete 

 circle on the segments anteriorly. Head as in Figure i, Plate LI I. 

 The structure of the antennae separates the two genera. 



Pupa (PI. LI. Fig. 6). — The antennae are shorter in Tabaiiiix 

 than in Chrysops, the thoracic spiracles are rather different in 

 structure, being more nearly vertical, and the abdominal armature dif- 

 fers as indicated in the preceding key to genera. 



Imago. — The hind tibiae differ from those of CJirysops in having; 

 apical spurs. From other Tabanidae possessing hind tibial spurs the 

 species may be distinguished by the 5-segmented third antennal joint, 

 with its distinct dorsal basal angle, and the absence of a cilia of hairs 

 on the hind tibia. 



HABITS OF LARVAE 



See under familv 



HABITS OE IMAGINES 



The species of this genus are verv serious pests of cattle, and 

 cause considerable loss to cattlemen in well- watered areas where thev 



