32 
Last segment ovate-conic. 
Smooth, tip of last segment rounded. Ludius. 
Punctate, tip of last segment with an acute point. 
. Elater. 
Last segment flattened, and with a subdentate margin 
apically. Melanotus. 
A pair of black pits at base of last segment, which is 
ovate-conic and pointed. Agriotes. 
Cerci present. Athous , Corymbites, Asapbes,Cryptohypnus. 
We have recognized five or six species of Melanotus larvae, two 
of which are definitely identified, and may be separated by the 
following key. Both have the body very finely and sparsely 
punctate, and the last segment finely tuberculate. 
Last segment finely, sparsely, and indistinctly punctate above, 
5-dentate apically, striae of muscular impressions at middle 
of body 12-14, sometimes fewer in younger specimens (PI. YI., 
Fig 5).;. communis. 
Last segment distinctly and rather coarsely punctate above, 
triangulate or feebly trident ate apically, striae of muscular 
impressions at middle of body 4—5, rarely fewer (PI. VI., Fig. 
L 8,). cribulosus. 
A larval skin like that of cribulosus , but with the apical teeth 
more narrow and prominent, especially the median one, was 
found in a pupal ceil with a fine male M. americanus. Another 
species frequently found in rotten wood, has the surface strongly 
punctate. 
Cakdiophorus sp. 
(Plate IV., Fig. 6.) 
A very peculiar long and slender elaterid larva, quite unlike a 
wireworm in general appearance, although belonging to the 
same family and doing the same mischief in the corn field, was 
found by me in 1886 mining and perforating the roots of corn 
in the sandy soil along the Mississippi in Alexander county, 
Illinois, with the effect to greatly delay the growth and perma¬ 
nently dwarf the corn. Although known only as a root insect, 
it probably attacks the kernel earlier, and its description is given 
here with that of other members of its family. It may be dis¬ 
tinguished at once from any other larva likely to occur in the 
same situation by its very long and slender form, and by its 
nodulated appearance, due to the expansion of a part of each 
segment. 
It is evidently capable of very serious injury to corn, chan¬ 
neling and burrowing the roots in every direction, and often 
causing decay—much more serious than the immediate mechan¬ 
ical injury of their mining. The perforations through the sur¬ 
face of the root were in some instances so numerous and close 
as practically to deprive the plant of all use of its roots. 
