64 
A SUMMARY HISTORY OF THE CORN-ROOT APHIS. 
(Aphis maidi-radicis, n. sp.*> 
The points of special interest in the history of the corn-root 
louse are the time and place of oviposition, the stage and place 
of hibernation, the relations of the root louse to the leaf louse 
of corn, the other food plants of each, and the relations of the 
root lice to ants. The account here given is based upon obser¬ 
vations and experiments made by myself and my assistants at 
the office, beginning with the year 1882. The facts concerning 
the laying of the eggs were ascertained by simple observation of 
the oviparous female in the field and in the laboratory. The 
method of hibernation was ascertained by field observations 
late in fall and early in spring. The statements made concern¬ 
ing food plants other than corn depend in part upon collections 
of the corn-root louse made on various plants (the identity of 
the species being verified in each case by successful maintenance 
and propagation on corn) and in part by the incidental trans¬ 
fer of corn lice to other vegetation in our breeding cages. 
The relations of the root lice to ants have been made out by 
very many and careful explorations of ants' nests in the field, by 
watching the operations of ants among the lice, by laboratory 
experiments with artificial ant colonies, and by various in¬ 
door experiments with ants deprived of lice, with lice deprived 
of ants, and the like. 
The connection between root and aerial forms of the plant 
louse has been studied by means of field observations intended 
to trace the first oligin of the latter in summer and their fate 
in autumn; and especially by oft-repeated breeding experi¬ 
ments with corn enclosed under cloth-covered frames. In* our 
latest experiments of this sort the cloth enclosures were made 
*The Aphis maidis of Fitch was described from examples of the leaf louse of corn, and 
the root louse has been since referred to the same species (first, by V alsh.but with a maik 
of doubt) on the purely gratuitous assumption that it was simply a root form of the other. 
Against this assumption I have now so large a body of experimental evidence that 1 no 
longer deem it proper to confuse the two. , 
During the present season (1891), for example, the root louse lias been reared on corn 
_— ^ \ ^ ^ nlnr. thovo ; Krw^o r\r icon cnnliniiciiclv frnm June tO 
leaves by confining females there in little bags of suisse continuously from 
September 19, no less than eight complete generations in succession having been thus pro¬ 
duced on the leaves. Those did not show the slightest tendency to approach the corn ear 
louse (the true Aphis maulis ) in any of the features of the species,but remained distinctly 
idemical with the louse of the roots. 
Descriptions of the species for which a name is here proposed may be found m th« 
Proceedings of the Entomological Society of Philadelphia, vol. i (1861-63), p. 300, and m the 
Transactions of the Illinois State Agricultural Society vol. 5 (1861-64), p. 492, (VV alsh); m Mis¬ 
cellaneous Essays on Economic Entomology,” 1886, p, 47, in the Fourteenth Pieport of the 
State Entomologist of Illinois, 1884, p. 25, and in Entomologica Americana, vol. 2(1898), p, 1/5. 
(Garman); and in ihe Bulletin of the Illinois State Laboratory of Natural History, vol. m, 
article xii, p. 213,1891, (Weed). 
