TABANUS, EARLY STAGES IN GENERAL. 



Much that can be said about Tahanus in general has been said 

 already under the family Tabanidae. 



The eggs of Tahanus are not appreciably different from those of 

 Chrysops, except that the latter resemble, according to Patton and 

 Cragg, more those of the smaller species of Tabanus, the eggs of the 

 larger species being of shghtly different form. According to Hart, 

 the eggs of Tabanus are always laid in clusters composed of several 

 layers, but recent observations have shown that from this rule ex- 

 ceptions are frequently met with, when the eggs are spread out in 

 one layer or even loosely scattered. As a rule, however, the eggs are 

 laid in a cone-shaped or bilaterally symmetrical mass containing 

 several layers of eggs and attached to various objects as specified 

 under the heading of Tabanidas. 



The larvae and pupae, studied by Hart, form two groups, which may 

 be called the lineola and the atratus groups. The larvae show the 

 most distinctive characteristics in the structure of the surface es- 

 pecially of the prothorax, which has lateral, dorsal, and ventral 

 shining areas, Hmited in front by an opaque pubescent annulus. 

 Comparing the anterior extension of these shining areas, Hart found 

 them all of about the same length in Chrysops and the lineola group 

 of Tabanus, although this length varies in Chrysops. The lateral 

 prothoracic areas are extensively invaded by the anterior annulus in 

 the atratus group of larvae, the striated shining space becoming basal, 

 being not more than half as long as the dorsal area. The upper 

 lateral space of the mesothorax is not closely striate, and is quite 

 shining. In all except some of the atratus group the remaining lat- 

 eral striation, including that of the prothorax, is not much finer, and 

 is also shining, but in the others, as in atratus, the prothoracic and 

 abdominal lateral striation becomes microscopically fine and even 

 subopaque. A smooth spot near the lower hind angle of the pro- 

 thoracic lateral area furnishes another good differential character. 

 The dorsal and ventral striation varies in extent according to age, 

 but the thorax is striated above in Chrysops, and smooth or nearly 



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