460 Bulletin No. 116. [August, 



kept burning all night for fourteen nights between May 20 and June 

 23 inclusive, and were visited at frequent intervals during each of 

 these nights. The weather was so cold during four nights that the 

 May-beetles were not flying, and no account is taken of these nights 

 in this discussion. 



The total product of t,he twelve traps, thus maintained for ten 

 entire nights, was 142 specimens of May-beetles of the genus Lach- 

 nosterna and 25 specimens of Cyclocephala. No account is taken of 

 the latter because their food habits are very dififerent from those of 

 Lachnosterna. The average product of a lantern in one night was 

 only 1.2' of the true May-beetles (Lachnosterna) , and the largest 

 catch of any one night was 40 specimens on June 18, or 3J^ per light. 

 The largest collections were made on three nights between June 9 

 and 18 inclusive, these averaging 33 per night, or about 3 to each 

 trap. The two collections of May, made on the 26th and 31st of 

 the month, averaged only 6 beetles per night, or i to each two traps. 



A single light-trap of the same kind, exposed at night without a 

 screen; for ten minutes May 21 and for thirty minutes May 23, close 

 to willow-trees at the border of this field and near the cemetery 

 above mentioned, yielded 1 1 May-beetles on the first night and 127 on 

 the second — seventy times as many taken in ten minutes by one trap 

 near these trees as were taken at approximately the same date by a 

 trap exposed all night in the open field. There could be no question, 

 consequently, that very nearly all the May-beetles of this neighbor- 

 hood were concentrated in the trees at this time. 



New data have been obtained by our collections and observations 

 of recent years with regard to the nightly movements of the beetles, 

 and these are thus summarized by Mr. J. A. West, who had charge 

 of this work for 1906. 



"There is a regular migration of beetles from the fields to the 

 trees in the evening. It takes place in June just about dusk — from a 

 few minutes before to a few minutes after eight p. m. The move- 

 ment of the beetles is almost simultaneous from the different fields. 

 An observer in one field can scarcely move to another and hope to 

 see the migration. It is usually but a few seconds from the time 

 its beginning is noticed in one place until a companion observer will 

 report its commencement perhaps a quarter of a mile away. Beetles 

 were found rising from the ground in fields of oats, in pasture, old 

 meadow, clover, alfalfa, and in corn. They were most abundant from 

 old pasture and least niunerous from alfalfa and corn. They were 

 observed coming from the ground in considerable numbers in oats 

 and clover fields. The following species are mentioned in the order 



