28 



BULLETIN 417, U. S. DEPARTMEXT OF AGRICULTURE. 



April 1, 1910, the following note was taken from a letter received 

 from Mr. J. J. Davis: "Several years ago at an electric light at 



Urbana, 111., I noticed 

 the species Calosoma 

 scrutator actively en- 

 gaged in eating the 

 June beetles as they 

 would light on the 

 pavement." No at- 

 tempts were made at 

 the laboratory to as- 

 certain the number of 

 different species of in- 

 sects upon which the 

 beetles would prey. 

 Daily feeding records 

 (see Table 2) were 

 kept of four pairs of 

 adults received about 

 the middle of May, 

 1909, the beetles 

 being supplied with 

 such food as was 

 most available at 

 that time. The bee- 

 tles were offered raw 

 meat, of which they 

 partook sp aringly 

 until about May 25, 

 when the caterpillars 

 of Malacosoma am- 

 ericana had reached 

 a fair size. The daily 

 records were then started and continued until the beetles either died 

 or entered hibernation in the fall. 



Table 2. — Feeding records of four pairs of Calosoma scrutator, 1909. 



II 





I 



K ^mi 





• 



■ 

 '"'•"fS 



JHJ4 



t : 



HI 







Fig. 4. — Calosoma scrutator feeding on a caterpillar in a large cage. 

 (Original.) 



Pair 

 No. 



Feeding 

 record 

 started. 



Ceased 

 feeding. 



Malaco- 

 soma 

 ameri- 

 cana, 



third to 

 sixth 

 stages. 



Porthc- 



tria dis- 



par, 



sixth 



stage . 



Hyphan- 



triacunea, 



third to 



sixth 



stages. 



Total. 



1772 

 1786 

 1787 

 1789 



May 16 

 26 

 23 

 26 



Sept. 24i 



July 232 



273 



Sept. 184 



315 

 234 

 336 

 277 



257 

 42 

 138 



194 



143 



715 

 276 

 474 



568 





97 





Average... 



508 















i Female died Aug. 11. 

 2 Female died June 26. 



Female died July 16. 

 Male died Aug. 25. 



All the pairs cited above reproduced as is shown in Table 4; this 

 accounts for the enormous amount of food eaten, which averaged 508 



