8 



BULLETIN 156, U. S. DEPARTMENT OF AGRICULTURE. 



this genus (Horlstoiiotus curiatus Say) as one of the worst pests in 

 South Carolina. 



Mr. Yernon King, of this office, is at present investigating a very 

 serious outbreak of Horistonotus uhlerii in Missouri and has pre- 

 pared the following preliminary account of this species : 



Horistonotus uhlerii Horn is a serious pest 

 to corn in southeastern Missouri, and to 

 corn, cotton, and cowpeas in northeastern 

 Arkansas, and has been reported from the 

 Carolinas and Illinois. 



The larvse may be found about the roots 

 of their host plants in large numbers, nearly 

 50 having been taken from one hill of corn. 

 Adults, pupse, and larva? can be seen in June, 

 all beneath the surface of the soil, and later 

 the adults will be found above the ground, 

 resting on the plants. The eggs are probably 

 laid about the end of June in the soil, on or 

 about the roots of corn and cowpeas, for 

 minute larvse have been taken early in July. 

 In May and June the larvae are most plenti- 

 ful, but as the season advances they become 

 scarce, and finally disappear by the time 

 winter sets in. By the third week in August 

 the adults can no longer be found. Under 

 laboratory conditions the larvse pass the 

 winter partly grown, and no doubt in nature 

 they hibernate in the same form, but in 

 what location is not yet known. 



Although corn, cowpeas, and cotton are 

 the main hosts of this insect, the larvse feed 

 on the roots of Johnson grass (Sorghum 

 halepcnse) and have been reported as feed- 

 ing on crab grass. 



Infested corn plants become wilted and 

 stunted, with leaves of a bluish shade, and 

 brown at the tips, standing out from the 

 stalk stiffly instead of bending over grace- 

 fully as in a healthy plant. Deprived of 

 most of the roots through the work of the 

 larvse, the plant c^n be pulled up with little 

 effort. Weak individuals soon succumb, leaving gaps in the rows, but the 

 more vigorous plants put forth new roots in abnormal numbers. These are 

 matted together and distorted, and although the plants survive, only nubbins 

 are produced. Tall and apparently healthy plants may have larvse among the 

 roots without damaging the corn materially. The infestation, therefore, is 

 not confined to the impoverished areas. 



In cowpeas the fibrous roots suffer most, the thicker roots being perforated, 

 so that the plants become yellow and dwarfed and fail to vine. 



Cotton is injured in the early stages by the larvse boring into the seed and 

 injuring the very young plants, checking the growth so much that the plant 

 dies or struggles along only to produce little or no cotton. 



Fig. 3. — The corn and cotton wire- 

 worm (Horistonotus uhlerii) : a, 

 Adult beetle : h, larva. Enlarged, 

 i Original, i 



