28 DEPARTMENT BULLETIN 1267, U. S. DEPT. OF AGRICULTURE 



DYSCINETUS TRACHYPYGUS (Burm.) 



The life history of Dyscinetus trachypygus agrees very closely 

 with that of Euetheola rugiceps. Development takes place at about 

 the same rate in both species. Both may occur in similar situations, 

 though D. trachypygus appears to be more tolerant of the products 



of organic putrefaction. Thus it has been 

 taken in both adult and larval stages in 

 compost heaps and in the vicinity of pig- 

 pens, situations in which E. rugiceps has 

 thus far never been found. There is no 

 evidence that the adults of this species 

 ever injure corn, as all experiments made 

 to test this possibility yielded only nega- 

 tive results. Farther south they attack 



fig. 15.— ventral view of head rice > and for that reason the species has 

 region of pupa of Dyscinetus been given the popular name of rice 



trachypygus. (Drawn by ^_ Qf i_55 

 Henry Fox) Deetle. 



The larva differs from that of E. rugiceps mainly in the entire 

 absence of anything suggestive of a median double row of modified 

 bristles on the last ventral segment (PL III, F). The surface of 

 the front of the head is sculptured as in E. rugiceps (PL III, A 

 and G). 



PUPA 



The pupa of D. trachypygus 

 (PL IV, G) is readily distin- 

 guished from that of E. rugi- 

 ceps by its longer and smoother 

 head and by the form of the 

 mouth parts. The mandibles 

 are much longer and more slen- 

 der than in either E. r-ugiceps 

 or L. gibhosus, and terminate 

 in a short, nearly truncate 

 apex which lies in contact with 

 the sides of the relatively small 

 labrum (fig. 15). The maxil- 

 lary palpi are unusually elon- 

 gate, with an acute apex, and 

 project considerably beyond the 

 general level of the other 

 mouth parts. The postcoxal 

 process of the presternum is 

 more nearly oblique and rather 



i i ~j- j-i „ •„ t? • Fig. 16. — Dyscmetus trachypygus: Adult, 



more blunt than m A. rugiceps. (Drawn by Henry Fox) 



D. trachypygus (fig. 16) may be readily recognized by its tooth- 

 less mandibles and by the form and smoothness of the head. The 

 latter is both longer and wider than in either Euetheola or Ligyrus 



