818 No. 59. 
— ited States Department of Agriculture, 
BUREAU OF ENTOMOLOGY, 
L. 0. HOWARD, Entomologist. 
THE CORN ROOT- WORMS. 
By F. H. CHITTENDEN, 
In Charge of Breeding Experiments. 
Among the many enemies of Indian corn two forms of slender, soft- 
bodied, whitish larvee known as root-worms are prominent through their 
injuries. When the plants are found to be withering or when the ears 
fail to fully develop, forming “ nubbins,”’ without any visible cause, the 
earth about the roots should be searched. It then frequently happens 
that root-worms are found at work. They operate somewhat in the 
manner of wireworms, and the two forms vary somewhat in the nature 
of their operations, as well as in the territory which they ravage. They 
are the young of two species of leaf-beetles of the family Chrysomelide 
and of the tribe Galerucini. 
The species which inhabits the middle western region is the western 
or northern corn root-worm (Diabrotica longicornis Say). Its injuries 
are practically confined to the middle West, where it would be a very 
serious pest were it not that progressive farmers in that region have 
adopted as a part of a sound agricultural routine a system of rotation 
which greatly reduces losses that might otherwise be sustained.! In 
spite, however, of the best methods of tillage, losses due to this insect 
are reckoned in millions of dollars annually. Thus Prof. F. M. Web- 
ster estimated the damage accomplished by this pest to corn in 24 ecoun- 
ties of Indiana alone in 1885 at nearly $2,000,000, this judgment being 
based on a loss of $16,000 sustained by one farmer and a personal knowl- 
edge of the destructive abundance of the insect throughout that State. 
The second species is the Southern corn root-worm (Diabrotica 12- 
punctata 01). It occurs generally throughout nearly the whole of the 
United States, but fortunately its injurious range is somewhat closely 
restricted to the southern States, though in recent years it is showing 
a disposition to extend depredations into more northern regions. 
The former species attacks first the fibrous roots and later the larger 
ones which it frequently destroys to such an extent that the infested 
plants may easily be pulled up by hand after they are seen to wither. 
The latter, at least in the maturing stage, eats directly into the stalk at 
a point near the upper whorl of roots. If injury by either species is not 
extensive, the ears, as previously stated, do not enbirely develop. 
1For more detailed information see Boren 18th Rept. St. Ent. Te 1891- 92 
(1894, pp. 146-165); Bul. 44, Univ. Ill., May, 1896, pp. 282-296 ; Westen Ind. 
Agl. Rept., 1885, author’s ed., pp. 6-10; Riley, Insect Life, Vol. IV, pp. 104-108. 
