28 DEPARTMENT BULLETIN 1267, U. S. DEPT. OF AGRICULTURE 
DYSCINETUS TRACHYPYGUS (Burm.) 
The life history of Dyscinetus trachypygus agrees very closely 
with that of Zwetheola 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 2. 7ugiceps 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 
Fic. 15.Ventral view of heaa Tice, and for that reason the species has 
region of pupa of Dyscinetus been given the popular nage eee 
trachypygus. (Drawn by bonkiee m Ti 
Henry Fox) eetile. 
LARVA 
The larva differs from that of /. rugiceps mainly in the entire 
absence of anything suggestive of a median double row of modified 
bristles on the last ventral segment (Pl. IlI, /). The surface of 
the front of the head is sculptured as in /. rugiceps (Pl. ILI, A 
and (). 
PUPA 
The pupa of D. trachypygus 
(Pl. IV, C) is readily distin- 
euished from that of 2. rugz- 
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 /’. rugiceps 
or L. gibbosus, and terminate 
in a short, nearly truncate 
apex which hes 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 prosternum is 
more nearly oblique and rather | { 
: . 7 oi) Fic. 16.—Dyscinetus trachypygus: Adult. 
more blunt than in /. rugiceps. (Drawn by Henry Fox) 
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ADULT 
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 
