March iSj7] DOANE: EaRLY StAGES OF DlABROTICA SOROR. 15 



THE IMMATURE STAGES OF DlABROTICA SOROR. 



By R. \V. Doane. 



[Mr. R. W. Doane, a student of entomology in this University 

 (Stanford), undertook during the college year 1895-96 the study of the 

 life-history of Diabrotica soror, the Pacific Coast representative of the 

 ■destructive Diabroticas. Despite the abundance of soror, its serious 

 ravages on flowers and fruits, and a lively interest on the part of ento- 

 mologists in its habits, its life history has remained unknown. By rea- 

 son of Mr. Doane's removal, his work, well begun and successfully 

 prosecuted as far as carried, has been interupted. The following de- 

 scriptions of the egg, larva and pupa, together with a few notes on the 

 habits of the species, are extracted from his notes. — Vernon L. Kellogg, 

 Stanford University, California.] 



The following descriptions were made from a number of specimens 

 taken in the field and laboratory. 



Egg. — Length, .7 mm.; width, 5 mm.; oval, dirty white in color ; 

 surface finely sculptured by minute hexagonal pitted areas. These 

 areas under a higher power lens show several irregular depressions 

 within their own surface. 



Full-grown larva. — Length, 12 mm.; width, 1.3 mm.; body 

 cylindrical, slightly tapeting toward the head ; the twelve segments be- 

 hind the head indistinctly separated. General color, except the head, 

 dorsal shield and last abdominal segment, dirty white, often becoming 

 more yellowish before pupation. Head dark brown above and on the 

 sides, same color as rest of body below ; posterior margin with a deep, 

 quite broad, V-shaped incision, ending in a broad deep suture which 

 runs cephalad for nearly one-third the length of the head, then divides 

 into two well-marked sutures which extend to the base of the antennae. 

 These sutures divide the head into three distinct parts, the anterior 

 part being the largest, the other two parts are equal and constitute the 

 posterior and part of the lateral portions of the head. There is a dark 

 median line ending at the tip of a small V-shaped incision in the anter- 

 ior margin of the head, and a few rather strong hairs scattered over the 

 surface of the head. Antennae white, three-jointed; first joint a little 

 broader than its length, second joint the shortest, narrower than the 

 first, third joint cone-shaped, its greatest width about equal to its 

 length. No eyes. Labrum same color as rest of the head. Mandibles 

 dark brown, darker at tips, other mouth parts and appendages whitish. 



