THE GENUS CALOSOMA. 89 



FIELD OBSERVATIONS AND ECONOMIC IMPORTANCE. 



Mr. C. N. Ainslie of this bureau under date of August 26, 1914, 

 observed a number of adults of this species in alfalfa fields infested 

 by Loxostege sp. at Friend, Nebr. The beetles were moving about 

 rapidly, so he did not see them feeding. One specimen was taken for 

 determination. 



May 26, 1914, Mr. T. S. Wilson of this bureau collected the adults 

 of this species on the ranges in New Mexico as early as May 26 in 1914. 

 During the week of June 10 the specimens were showing up quite 

 commonly. June 17 Mr. Caffrey states that the adults were noted to 

 be present in abundance. Approximately 25 or 30 were seen in one- 

 half hour. Hemileuca and Malacosoma larvae were abundant in the 

 vicinity. August 9 several of the beetles were observed on the slopes 

 of Eagle Tail Mountain, N. Mex. 



Mr. Walton and others observed the beetle larvae feeding upon 

 caterpillars and pupae of H. oliviae in the field, the beetle larvae seizing 

 its prey in the usual manner for Calosoma in general and holding on 

 until the caterpillar is subdued and a puncture effected with the man- 

 dibles. The body contents then ooze out in part and the beetle 

 larva feeds until its appetite is satiated. In one instance, an adult 

 beetle was noted feeding upon a male Hemileuca moth. 



The beetles and their larvae were found in practically all parts of a 

 range infested with H. oliviae Ckll. but were noted more commonly 

 near wooded areas. The adults and larvae were noted feeding on pupae 

 of II. oliviae through the coarse meshes of the cocoon. These cocoons 

 and pupae were often located in weeds and grasses from 2 to 6 inches 

 above ground and the fact that the beetle larvae had found their prey 

 in these situations indicates their ability to climb and their impor- 

 tance as an enemy of such a caterpillar pest. 



Mr. H. F. Wickham conducted some investigations with this spe- 

 cies along with 0. haydeni Say by supplying both killed and living 

 grasshoppers along with H. oliviae larvae as food for the beetles to 

 determine their preference with reference to accessibility of same. 

 The results were similar for each species of beetle and are recorded 

 under C. haydeni Say. 



BRIEF DESCRIPTION OF LARVA. 



First stage. Rather slender larva. Average length of five newly-hatched speci- 

 mens that had been preserved in alcohol, 10 mm.; width, 1.9 mm.; color, black dor- 

 sally, ventral plates grayish-brown. Ventral plates ordinarily containing one and 

 two long brown hairs and sometimes other shorter ones. Caudal appendages rather 

 stout (1.3 mm. long), slender, projecting obliquely backward. 



Second stage. Form similar to first stage. Average length of six specimens, 16.6 

 mm.; width, 3 mm. Caudal appendages bearing short acute protuberance dorsally 

 beyond middle on each and curving slightly downward beyond these. Dorsum 

 shining black and ventral plates dark brown in this stage. 



Third stage (PI. XVII, D). Rather slender larva. Average length of five almost 

 mature specimens, 26 mm.; width, 4.6 mm. Caudal appendages rather stout (1.3 

 mm. long) and erect, curving backward after dorsal protuberance. Appendages 

 widely separated at base, tapering to a point abruptly beyond dorsal protuberance, 

 which is located about two-thirds the length of each appendage. Color shining black 

 above, dark brown below. Ventral plates sparsely clothed with hairs. Anterior 

 ventral plates 2 to 7, inclusive, oval in form, dilated in middle, sometimes notched 

 posteriorly in the center, also containing a small median keel more prominent near 

 the posterior margin. Posterior angles of anal segment narrow at base, slightly turned 

 upward into a long blunt point with stout spine at apex. Posterior angles of tergite 

 of penultimate segment projecting backward rather pointedly. 



