Peo bte EIN OF THE, 
USDEPARTMENT OFAGRICULIURE 
No. 8 




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Contribution from the Bureau of Entomology, L. O. Howard, Chief. 
September 27, 1913. 
THE WESTERN CORN ROOTWORM. 
By EF. M. WEBSTER, 
In Charge of Cereal and Forage Insect Investigations. 
INTRODUCTION. 
The western corn rootworm (Liabrotica longicornis Say) derives 
its common name from the fact that the larva (fig. 1) was first 
observed attacking the roots of corn in the Middle West. Its larval 
habits, its life evcle, and the appearance of the adult insect (fig. 2) 
are all entirely different from those of the southern corn rootworm 
(Diabrotica duodecimpunctata Oliv.), though the worms themselves 
are exceedingly alike in appearance. In figure 1 the larva is ex- 
tended at full length, as when feeding, having 
been drawn from living individuals. 
The beetles (fig. 2) in life are about the size 
of the striped cucumber beetle (Diabrotica 
vittata Fab.), but smaller and less robust than 
the southern corn rootworm, and are entirely 
of a green or yellowish-green color, except the 
eyes, which are black. The farmer will be 
most likely to observe these feeding among 
the silk of the 
ears and the 
pollen of corn 

C ] %, Fie. 2.—The western corn 
during late Au Fig. 1.—The western corn rootworm rootworm: Adult, or 
gust and Sep- (Diabrotica longicornis) : Larva, or beetle; a, claw of hind 
“worm.” $Much enlarged. (Origi- leg. Much enlarged. 
tember, though _ ,,)) (Original. ) 
the writer has 
seen them enter houses in the country at night, being attracted by 
the evening lamps. An abundance of these beetles in a cornfield 
should be a distinct warning that the field should not be planted to 
corn the following year, but that it should be devoted to wheat, oats, 
barley. rve, or to any crop other than corn. | 
. SEASONAL HISTORY. 
The eggs (fig. 3) are minute, yellowish-white objects, having to 
the unaided eye much the appearance of minute grains of white sand. 
6135°——18 
