February, '16] ENTOiMOLOGlSTS' DISCUSSIONS 135 



point I was rather interested in — he speaks about the differences of 

 distribution of species in small areas. In Minnesota we find a pre- 

 dominance of L. fusca in southeast Minneapolis, while in St. Anthony 

 Park, three or four miles distant, we found L. rugosa most abundant. 

 In Stillwater there is a large per cent of fusca and duhia. We found 

 duhia and grandis were northern species. On the north border in 

 collecting we found them very abundant on the west and again while 

 coming in on the eastern border, while the central showed grandis 

 most abundant. One collection at Stillwater, where we worked 

 three-fourths of an hour, we found grandis, duhia and fusca, I was 

 surprised at the predominance of females as you usually find a pre- 

 dominance of males. 



Mr. J. G. Sanders: In taking records of individuals it is necessary 

 to 'make note of the rate found in the early part of the flying season. 

 After the middle of the season we find ten to one oi fusca. 



Mrs. L. C. R. Smyth: I happen to be rather familiar with the life- 

 histories in Porto Rico and was interested in one of the discussions with 

 regard to variation of occurrences. Porto Rico is some forty miles 

 wide and the species that occur on the northern portion are quite dis- 

 tinct from those on the southern. They have not been identified 

 but have been given locality names. 



The life-history of one species covers a period of from two to five 

 years. I happen to know that in Porto Rico the life-history of another 

 species of white grub has been shortened to seven months, from the 

 laying of the egg to the issuance of the adult beetle. A number of 

 species may pass their life-history in thirteen months. The cli- 

 matic conditions are such that they do not need to bore deep into the 

 earth. The average temperature in summer is 72° and in winter 70°. 



Mr. J. J. Davis: I would add that there seem to be at least three 

 factors limiting the distribution of different species, namely — soil, 

 trees and elevation. Certain species are found in sandy soils which 

 do not occur elsewhere and vice versa. The food preference of the 

 different species of beetles varies considerably as is shown by our 

 collection records. The effect of elevation is well shown by our 

 collections at Lafayette where we have three elevations; one along the 

 Wabash River which is sometimes overflowed, one a little higher up, 

 say about 75 feet, and a third about two miles back which is probably 

 75 to 100 feet higher than the second elevation. In the lowest area 

 at Lafayette and in the low ground elsewhere in the state we find 

 Lachnosterna vehemens common and not occurring at the higher eleva- 

 tions and adversely we find species which occur only on the highest 

 elevations. 



Adjournment, 5.00 p. m. 



