April, '13] DAVIS^: LACHNOSTERXA TRISTIS FABR 277 



species was studied by Mr. Theodore Pergande from 1893 to 1895 

 and found to have a life cycle of practically^ three j^ears, in the latitude 

 of Washington, D. C, remaining in the grub stage parts of three 

 years, the total larval period being slightly over twenty-five months. 

 It has been the general opinion that all Lachnosterna have a three 

 year life cycle in the northern States and we have much data both 

 from artificial breeding experiments and from field observations to 

 prove that this is the case for manj^ species. One species (Lachno- 

 sterna tristis), however, has been found by us to be an exception to 

 the rule, it having a life cycle of only two years. 



Several pairs of L. tristis, collected in copula on oak at Lafayette, 

 Indiana, May 13 and 17, 1911, were confined in two twelve-inch 

 standard flower pots which had previously been filled with soil, the 

 top sodded and the pots themselves sunk into the ground. The beetles 

 lived on an average of about two weeks, a rather short period in com- 

 parison with other species of Lachnosterna. During life the beetles 

 were supplied with fresh oak foliage every few nights and they were 

 out feeding every night, excepting when too cold or stormy, re-enter- 

 ing the soil each morning. The cages were examined October 9, 1911, 

 and it was then observed that the grubs in these cages were as large 

 or larger than the same aged grubs of other species, although the 

 adults of tristis are much smaller than adults of these other species. 

 Owing to the shallowness of the pots the grubs coi^ld not enter the 

 soil as deeply as under natural conditions, and it was therefore neces- 

 sary to cover the tops with a light mulch of manure. Even with the 

 mulch the soil in the pots became saturated with moisture and for 

 several months it was frozen solid. Notwithstanding these apparently 

 unfavorable conditions live grubs were found when the soil thawed 

 in the spring. Complete examinations of both cages were made 

 September 23, 1912, a single adult female tristis being found in one cage, 

 while one male and one female were found in the second cage, all 

 occurring in the pupal cells and within an inch of the bottom of the 

 pots which were filled with ten and one-half inches of soil. In neither 

 cage were grubs or pupae found. These beetles would have emerged 

 in the spring of 1913, which gives a period of two years from the time 

 the eggs are laid until the appearance of the adults above ground, 

 the total length of the grub stage being about one year. All other 

 species of Lachnosterna being studied at Lafayette have a life cycle 

 of more than two years, probably all having a three year cycle, al- 

 though definite data will not be obtainable for these species until 

 this fall. 



From our present meagre data on the economy of this species I 

 conclude that it is one of the least economically important species of 



