DELTOCEPHALUS SONORUS BALL. 
79 
marked. It is yellowish in color, has two black dots on the margin 
of the upper surface, and often two oblique dashes on the disk. The 
last nymphal stage further presents very distinct spots — those on the 
front margin of the wing pads and a number on the hinder end of the 
disk which are more or less distinctly arranged in transverse rows . The 
nymph is not very readily separated from that of Athysanus exitiosus, 
but the latter species has black spots on the head farther down upon 
the front. The nymphs of this species appear in early summer and the 
adults are usually to be found in numbers by the first of July. These 
adults deposit eggs 
and the nymphs 
from these develop 
during July and Au- 
gust, and adults ap- 
pear in September 
and are to be found 
on into October and 
November and in 
localities farther 
south will be taken 
in numbers as late 
as during Novem- 
ber and early De- 
cember. In fact, they seem to remain 
weather forces them into inactivity. 
Fig. 14.— The black- faced leafhopper (Deltocephalus nigrifrons): a, Dorsal 
view; b, vertex and prono turn; c, face; d, female genitalia; e, male geni- 
talia; /, wing. All enlarged. (Original.) 
active until severe cold 
MEANS OF CONTROL. 
The method of control for this species may be based directly upon 
the migratory habit of the species and especially upon the fact that 
it develops so largely in the field grasses which are either worthless or 
noxious in character. In many places the mere elimination of fox- 
tails and panics which grow along the borders or in neglected corn- 
fields would greatly reduce the numbers of this pest, and in some 
instances it would be entirely practicable to burn the borders of fields, 
where such grasses are beginning to wither, in time to kill the hoppers 
which may occur there. In the Southern States, especially where 
fields are often interspersed with strips of uncultivated ground, the 
burning or even close mowing of such strips would doubtless be of 
considerable service in preventing injury to fall wheat and oats. 
Additional knowledge concerning the actual method of deposition 
of eggs may add to the possible measures for control. 
Deltocephalus sonorus Ball. 
The species Deltocephalus sonorus Ball is one of the nigrifrons group, 
but is uniformly smaller and more slender, and the spots on the border 
of the vertex are quite constantly arranged so that there is a small 
29460°— Bull. 108—12 6 
