NORTH AMERICAN GEOTRUPINAE — HOWDEN 241 



many beetles in a small enclosure, etc. Fortunately, a large natural 

 colony of blackburnii was discovered at Faison, N. C, and digging 

 there over the summer showed the development of the larvae in the 

 cage closely approximated that found in the Faison woods (pi. 16, 

 fig. 1). 



One blackburnii larva was found in a pasture at Mills River, N. C, 

 and the time of its pupation and emergence was the same as many 

 of the larvae taken from Faison. 



Before discussing the length of the various stages of development, 

 the burrow and larval food should be mentioned. On the average the 

 burrows of Geotrupes blackburnii were the shallowest of any of the 

 species of Geotrupes studied. The vertical feeding burrows, which 

 were 4 to 8 inches deep, were often deeper than the burrows having 

 the larval cell at the bottom. 



Table 3. — Bait used in traps and number of Geotrupes blackburnii blackburnii 

 Fabricius collected at Raleigh, N. C. 



(First column under month refers to first two weeks, second column to last two 



weeks) 



Chemical Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Total 



Propionic acid 632622000000000002236 11 26 7 78 



n-Butyric acid 7713093000000000000 13 3213 52 



Oleic acid 000000000000000000000000 



Isoamylamine.... 000000100000000000000000 1 



Valeric acid 000000000000000000000000 



n-Amyl mercaptan 000000000000000000020000 2 



Pelargonic acid 00000000000000000000000 



Ethyl mercaptan 00000000000000000000000 



Total.. 13 10 3 9 2 11 4 2 2 18 9 13 27 10 133 



The brood burrows found at Faison, where the soil was a sandy 

 loam, were from 3% to 6)2 inches deep, with an average depth of 4 

 inches. The one burrow found at MUls River went to a depth of 5 

 inches into the hard red clay. In the enclosure at Raleigh, where the 

 soil was not well packed, the burrows were slightly deeper, from 

 4K to 9 inches, with an average depth of 6 to 7 inches. All the mea- 

 surements given refer to the vertical distance between the point where 

 the larva was found and the ground surface. 



In the matter of larval food, blackburnii seemed to show a gi-eater 

 plasticity than did other species. The larval cell at Mills River and 

 all of those at Raleigh were composed of fairly old cow dung, while 

 those at Faison, whUe they may have contained some dung, also had 

 bits of leaves and grass m^aking up part of the wad. At the time the 

 colony was found the larvae had largely eaten out the center of the 

 wad, which may have been composed of dung. If this were true, it 

 was not cow dung, as no cow had been in the woods for a number of 

 years. 



