March 11 eight successive generations apppeared—practically eleven 
days to each generation. - 
Transfer of Leaf Lace to Roots of other Plants—A few experi- 
ments of this sort, made in October, 1887, and in September, 1890, 
were quite without result, the plant lice neither feeding nor breeding at 
that season of the year on roots of purslane.or corn. ‘They simply tried 
to escape, and died if prevented. A similar experiment tried with 
purslane in October, 1888, had a similar issue. 
NATURAL ENEMIES. 
Although various insect species, mites, ground beetles, and the like, 
have been found in more or less suspicious relation to the corn root lice 
in our breeding cages, and even in the fields, no known case has oc- 
curred to us of destruction by an insect enemy. It is, indeed, a remarkable 
fact that not a single hymenopterous parasite has ever been bred from 
- the corn root aphis in all our long experience with that insect. It is 
true that root lice are much less parasitized than those feeding in more 
exposed positions, but they are nevertheless by no means commonly free 
from parasitic attack. 
The only natural check upon the increase of this root aphis which 
has come immediately to our notice is a parasitic fungus, Hntomophthora 
fresenu, detected October 16, 1889, infesting sexual individuals of 
this species found on roots of the curled dock (Rumex crispus) at Cham- 
paign, Illinois. Affected specimens were of a creamy or whitish color, 
and were literally crammed with the small oval granular spores of 
the Entomophthora. These so-called spores (properly “conidia”) are 
commonly of a smoky tint with a clearly distinguishable cell wall and 
granular contents. They measure 18-20 microns in length by 15-18 
in width. They are nearly spherical to short ovoid, and often have a short 
truncate, or slightly papillate, base. The fatal disease characterized 
by this fungus was generally distributed among the corn root lice in 
the field in which it was observed, nearly every lot of root lice detected 
there giving us examples of it, but it was not detected elsewhere, and 
an attempt to extend it by contagion to the corn leaf aphis (A. maidis) 
resulted unsuccessfully. 
This fungus parasite is, so far as known, confined to the species of 
plant lice, of which it infests a great number. It is reported by Thaxter, 
in his “Entomophthoree of the United States,”* to occur in Maine, 
Massachusetts, North Carolina, and Europe. 
ECONOMIC PROCEDURE. 
Our present knowledge of the life history of the corn plant louse 
suggests four possible methods of attack. (1) We may try the effect 
of a change of crop after any notable plant-louse injury to corn, in the 
expectation that corn planted on ground which contains no plant-louse 
eggs will become so slightly or so slowly infested, if at all, that no 
harm need be anticipated. (2) We may resort to fertilizers and other 
- applications made to the young corn hill in spring in the hope of killing 
the lice outright or of supporting the plant against their attack at a 
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. *A full account of this Entomophthora is given in the paper cited. (See Mem. 
Bost. Soc. Nat. Hist. Vol IV., No. 6, p. 168.) 
