[1911] Larva of Calosoma Sycophanta. 179 



If the traveling capacity is compared on the basis of weight 

 the difference is much greater. The average weight of the beetle 

 larva is 19.8 m. g., that of the rat 5250 m. g., and that of the 

 guinea pig 7500 m. g. Thus if the rate of travel was in the 

 same proportion the rat would cover 453 miles and the guinea 

 pig 64S miles while the larva traveled 1.71 miles. 



The length of life of the insect is also worthy of note when it is 

 remembered that no food or water was supplied, as it indicates 

 that the young larvae are able to survive several days in the 

 field without food and still have sufficient vitality to make a 

 thorough and active search for their prey. 



DISCUSSION. 



Mr. J. B. Smith: The thing that interested me most is the 

 appropriateness of the German name, "laufkafer. " Mr. Bur- 

 gess' paper shows that the German name is absolutely correct 

 when applied to the larva of this insect, because it certainly 

 can run. 



Mr. Howard: It is estimated that there are now over a 

 million of these insects in Massachusetts, that next year there 

 will be ten millions, and the year after one hundred millions. 



Mr. J. B. Smith: Dr. Howard's remark recalls to my mind 

 the following experience: In south New Jersey there was one 

 season an outbreak of a species of Geometrid caterpillar, which 

 covered the scrub oaks in enormous numbers, and that season, 

 in company with two or three entomologists, I was down in the 

 region where the insects occurred. We found Calosoma of 

 two species, willcoxi and scrutator, were present in enormous 

 numbers on the young oak trees, feeding upon these larvae. 

 The next year you could look through the whole territory and 

 could not find a single specimen of either species. 



Mr. Burgess: I think a possible explanation might be 

 that, as far as we know the larvae of Calosoma willcoxi and 

 scrutator do not climb trees, while the larva of sycophanta 

 does so very readily. 



Mr. Summers: This certainly is an interesting paper, but 

 the point that is perhaps the most interesting is the comparison 

 of the rat and the guinea pig. It seems to me that is a fallacy 



