■ 
Taking the acreage for com in Illinois as 6,586,201, the 
nnber given in the report of our State Agricultural Department 
(.182, an average loss in a year of as little as one bushel to 
ten acres would amount to about 658,620 bushels of corn, rep- 
ung at least $100,000 in money, an amount sufficient to pay 
ixpenses of a State Entomologist for fifty years, 
NOMENCLATURE. 
ft* 
those who have written upon the corn louse, with the excep- 
>f Prof. Forbes, have used without question the technical name 
7naidis. There can be little doubt, however, that the corn plant 
belongs to the genus Rhopalosiphum, as this genus is used 
e great authorities on the classification of aphides. The char- 
stic swollen cornicles are not as well marked as in some mem- 
Sf the genus Rhopalosiphum, but will serve at a glance to dis- 
sh this species from members of the genus Aphis. The old 
has so frequently appeared in these reports that a change is 
eemed desirable here. 
' I 
DESCRIPTION. 
'iged viviparous female [root form].—Head black. Thorax brown- 
jack. Abdomen above pale green with about three marginal 
spots and numerous small, dark specks over the surface, 
tnae dark with pale at the articulations. Prothorax pale in the 
e; meso- and metathorax chiefly brown. Cornicles black with 
black at their bases, chiefly inside. Cauda dusky, with several 
7,erse dusky marks before it. Thorax chiefly dark below, with 
paces about bases of limbs brownish. Under side of the abdo- 
I pale green ; two transverse dark marks before the cauda. Legs 
y black; tibiae for basal two-thirds pale. Length of body 1.8 
width of body, .9 mm.; antennae, .7 mm; cornicles, .12 mm.; 
2 mm. 
>a of winged ' viviparous female [root form].—Head obscurely 
. Thorax obscure reddish brown. Abdomen above pale dull 
j, without spots. Antennoe dusky only at tip. Eyes reddish- 
! i. Wing-pads obscurely dusky. Cornicles black. Cauda dusky, 
•al color below greenish. Rostrum dark at base and tip. Tarsi 
ips of tibiae dusky. Length of body, 1.61 mm.; width of body, 
; [n. 
agless viviparous female [root form].—Head black above. Pro- 
pic segment black; the following three body segments each 
a transverse dusky mark on their middles. Abdomen pale 
| with black marginal spots and with numerous smaller specks 
the surface. Antennae dusky at tip and slightly also at 
Eyes reddish brown. Cornicles black. Cauda dusky ; pre- 
by two transverse black marks. Abdomen beneath with two 
^erse black marks before the cauda, otherwise nearly uniform 
peen below, Rostrum black at base and tip. Coxae, femora 
7, tips of tibiae and the tarsi black. Body widely oval in out- 
Antennae short, about half the length of the body and head; 
md second articles equal in length, first largest; third article 
