178 Annals Entomological Society of America [Vol. IV, 



on its back and remained so until 4.05 A. M. when upon being 

 touched in order to test life it grappled the lead pencil point 

 and again regained its footing. It moved and backed in a 

 small circle at 5.15 A. M. At 7.05 A. M. it fell on its back again, 

 and remained there until it died at 8.40 A. M., June 21. 



The rate of travel from 8.30 A. M., June 20, to 8.40 a. m., 

 the following morning, which was the last twenty-four hours 

 of the insect's life, is shown in the diagram (Fig. 2.) and 

 illustrates how remarkable was the activity until almost the 

 close of its life. ■ 



No delicate balances were available for weighing the larva 

 after it hatched, but as soon as it died it was weighed by Mr. 

 W. G. Fall, of the Massachusetts Department of Weights and 

 Measures in Boston. The average weight of ten newly hatched 

 larvae was .2973 grains; the weight of the dead larva was .18 

 grains, which indicates that it lost .1173 grains during the 

 experiment. 



Although the distance traveled is probably much greater 

 than what would actually occur in nature, it is remarkable that 

 so much latent energy can be stored up in an egg of one of these 

 beetles. It is interesting to compare the ability to travel 

 possessed by this larva with that of some of the higher animals. 

 Through the courtesy of Dr. W. E. Castle and his assistant 

 Mr. Detlefson, of the Bussey Institution, of Harvard Univer- 

 sity, we have been able to secure measurements and weights of 

 young rats and guinea pigs and this information is used in mak- 

 ing the comparison. The average length of all the legs of the 

 larva of Calosoma sycophanta, ten specimens having been meas- 

 ured, was 3.37 mm., that of a young rat, one to three days old 

 twelve specimens having been measured, was 19.08 mm., or 

 5 2-3 times greater, while similar measurements of a guinea pig 

 showed that the average length of leg was 76.25 mm., or 22 ] 2 

 times greater than that of the beetle larva. If the ability to travel 

 of the higher animals mentioned equalled that of sycophanta, 

 the rat would be able to cover nine miles without food or water, 

 while the guinea pig would have to cover over 38 miles under 

 the same conditions. It might be said that the locomotive 

 powers of a young guinea pig are superior to that of a rat of the 

 same age but doubtless either would die before traveling a very 

 short distance to obtain food. 



