ART. 17. LARVAE OF HOLARCTIC TIGER-BEETLES HAMILTON. 35 



aspect of head and pronotum white or transparent, the other setae 

 brown. 



Head. — Setae on dorsal aspect medium length, prominent; diame- 

 ter of ocellus 2 equal to the distance between ocelli 1 and 2; fronto- 

 clypeo-labral area almost as long as broad; U-shaped ridge on the 

 caudal part of frons bearing two setae; antenna with the proximal 

 segment slightly shorter than the second, the third a little more 

 than two-thirds and the distal one-third the length of the second, 

 the proximal segment with 5 or 6 setae and the second with 9 or 

 10; maxilla with the proximal segment of the galea bearing three 

 setae on its mesal margin, maxillary palpus three-segmented; ligula 

 with four fine setae not arranged in a transverse row at its ventro- 

 distal end, proximal segment of labial palpus with three spine- 

 like projections on the ventro-distal margin and with two setae on 

 each side of these spines, the proximal segment with four setae and 

 the distal segment with one. 



Thorax. — Pronotum with the cephalo-lateral angles extending 

 almost as far cephalad as the mesal portion, lateral margins slightly 

 carinate, primary setae medium size, prominent, secondary setae 

 medium size and few in number (fig. 152). 



Abdomen. — Chitinized areas not distinct, secondary setae short 

 and not numerous (fig. 164) ; ninth abdominal sternum with the 

 caudal margin bearing two groups of five setae each ; median hooks 

 with three or four setae; inner hooks with two setae, the inner seta 

 located nearer the base of the hook than the outer one, the spinelike 

 projection one-half the length of the hook (fig. 178). 



Measurements. — Length of larvae, 25 to 27 mm., width at the 

 third abdominal segment, 3.5 to 4 mm.; diameter of ocellus 2, 0.37 

 to 0.38 mm. ; distance between ocelli 1 and 2, 0.37 to 0.38 mm. ; length 

 of fronto-clypeo-labral area, 2.3 to 2.4 mm., width, 2.4 to 2.6 mm.; 

 length of pronotum, 2.9 to 3.1 mm., width, 4.6 to 4.9 mm. 



The larvae of this species may be distinguished from the preced- 

 ing by the longer spinelike projection of the inner hook and the 

 inner seta on the hook being located nearer the base than the outer 

 seta, also by the less numerous secondary setae on the pronotum and 

 its distinctly larger head measurements. 



The larvae were collected at Haswell, Colorado, on the open prairie 

 in clay or adobe soil. The burrows occurred between bunches of 

 grass, were about 8 inches deep, slightly spiral, and two-fifths of an 

 inch in diameter at the bottom. Smaller larvae collected in the 

 same situation and which appeared to be immature larvae of this 

 species had a chimney-like structure about an inch long around the 

 opening of the burrow. This addition was about an inch long and 

 was built so that it was parallel to the surface of the ground. 



