46 



CEREAL AXD FORAGE INSECTS. 



a short petiole, a few bristly hairs not arranged in whorls scattered over each joint' 

 in the male, joints 3 to 14 are each greatly constricted, slightly before the middle, 

 and again at the apex except in the case of the last joint, the constricted portions 

 arc as long as the thickening at the base of each joint; each of the thickened por- 

 tions bears a whorl of bristly hairs. In the living insect the head, including the palpi, 

 h yellow, antennae and legs brown, thorax orange red, the center of the mesonotum 

 and a spot crossing the pleura and enlarging on the sternum black, abdomen orange red, 

 wings grayish hyaline. The first vein reaches the costa noticeably before the middle 

 of the wing; third vein nearly straight, ending slightly below the extreme tip of the 

 wing, the basal portion of this vein, where it joins the first vein, distinct; fifth vein 

 forked slightly before the middle of the wing, its anterior fork ending nearly mid- 

 way between the tip of the pos- 

 terior fork and the apex of the 

 third vein . Length nearly 2 mm 



The male (fig. 24, a), as 

 indicated in Mr. Coquil- 

 lett/s description, is pro- 

 vided with antennae which 

 exceed in length those of 

 the female and which differ 

 greatly in the structure of 

 their joints, while on the 

 wing the former charac- 

 teristic serves to distin- 

 guish the sexes; also, the 

 movements of the male are 

 much quicker than those 

 of the female. 



The female (fig. 25, a) to 

 superficial examination, at 

 rest or on the wing, appears 

 more robust than the male 



Fig. 25.-The sorghum midge: a, Adult female, dorsal view; ftnd at the same time her 

 6, antennal joints of same; c, eggs; d, fully developed larva 



as found in cocoon, showing characteristic cecidomyiid movements are much more 

 "breastbone"; e larva in early stage;/ , pupa ad, e,f, deliberate and slow. She 



Greatly enlarged; b, c, highly magnified. (Original.) 



is provided with a delicate 

 hairlike ovipositor, capable of great extension during the process of 

 oviposition. Often its length exceeds that of the entire body. The 

 following measurements of average male and female midges serve to 

 illustrate the comparative dimensions of the two sexes: 



Table I. — Comparative measurements of males and females of the sorghum midge 



( Con tarinia sorghico la) . 



Measurement. 



Length of body (antennae 



excluded) 



Length of antennae 



Length of ovipositor. 

 Total length 



Adult 

 female. 



Adult male. 



Measurement. 



Adult 

 female. 



Adult male. 



Milli- 



Milli- 



meters. 



meters. 



1.78 



1.22 



.843 



1.05 



1.64 





4.36 



2.27 



Milli- 

 meters. 



Width of thorax 0. 45 



Length of wing 1.87 



Wing expanse 4. 19 



Milli- 

 meters. 



0.27 

 .85 



1.98 



