THE DESEET COKIT FLEA-BEETLE, 15 



time be protected from the heat. In feeding a beetle will stand 

 crosswise on a corn leaf and with its strong mandibles eat out a 

 portion of the epidermis between two parallel veins, continuing in a 

 straight Ime, often 1 or 2 inches m length. They rarely eat a hole 

 entirely thi-ough a leaf. In cases where extremely heavy feeding 

 occurs and where the infestation is great, the green portion is entirely 

 psaten out, and the leaf has a burned or scarred appearance. 



SEASONAL HISTORY. 



NUMBER OF GENERATIONS ANNUALLY. 



The desert corn flea-beetle usually appears about the middle of 

 February each spring. The time at which the beetles may first be 

 fomid actively feeding in the field wiU, of course, depend upon the 

 season. In the year 1912 Mr. R. N. Wilson first took these beetles 

 on February 14, sweeping a few specimens from a barley field. In 

 1913 the same observer took a few feeding beetles on January 13. 

 The month of January of that year, however, was quite warm and 

 advanced over the ordinary year. In the year 1914 Mr. D. J. Caffrey 

 took adults for the first time on February 20. These were feeding in a 

 green wheat field. In the sprmg of 1915 Mr. F. H. Gates first swept 

 adults in an alfalfa field on February 9. They did not, however, 

 become abundant until February 23, when both the author and 

 Mr. Gates secured an abundance of this species. 



It is only a few weeks after emergence that these hibernating 

 adults begin depositing eggs. The earliest date that eggs have been 

 secured in cages was March 12, 1915, at which time the writer secured 

 .eggs in considerable numbers. There are from three to four genera- 

 tions each year in the Salt River VaUe3^ The first generation, starting 

 with eggs deposited in early March, appears about the first of June. 

 Another generation quickly follows, adults co: ling forth about the 

 middle of July, a third generation is completed by the first to the 

 middle of September, and in occasional years there is a partial fourth 

 generation. 



The fact, however, that the length of eacii individual life cycle is 

 determined quite largely by the proximity of both larva) and pup£e 

 to the surface of the ground is responsible for the generjil inter- 

 mingling of the various generations, so that eggs may be secured 

 tliroughoiit the breeding season. Eggs have been secured in cages 

 tlirouglioiittli<;year,b(!ginningwit)i tlu^ fii-st of Marcliand contiinjingto 

 t}i(;nii'i(lJcof October. Mr. Wilson liass(!cure<l eggs in cages dmhig the 

 months of May, June, -inly, August, September, and October, while 

 the writer has s(!cur('(l eggs (hirir)g Mandi, A[)ril, May, and June, and 

 t hcsc v('a:<)V(\s were foJIowcd up ])y those of Messrs. Hogg and Newton, 

 who ohtairu'd eggs (hiring July, August, and September of tlio same 

 year. Of course, eggs deposited I he hist of ()ctolK>i- would, or(U- 



