74 
covered it within. October 30 these leaf lice were still breeding 
freely on the corn, and likewise on wheat plants exposed to them 
under the same cover, producing both winged and wingless in¬ 
dividuals. These conditions remained substantially unchanged, 
the lice breeding freely in all thq inclosures in the insectary until 
March 19, 1889, when the experiment was discontinued with a 
considerable supply of these aerial lice still in our possession. 
February 14 one lot under a bell jar was placed outdoors to de¬ 
termine the effect of a change of temperature. This lot was not 
examined again until March 4, when all were dead, with no 
trace of eggs, however, on the plants. Between September 11 
and March 11 eight successive generations appeared -practically 
eleven davs to each generation. 
D 
Transfer of Leaf Lice to Roots oi other Plants—A. few ex¬ 
periments of this sort, made in October, 1887, and in Septem¬ 
ber, 1890, were quite without result, the plant lice neither feed¬ 
ing 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 occurred to us of destruction by an insect enemy. 
It is, indeed, a remarkable fact that not a single hvmenopter- 
ous 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, 
Entomophthora fresenii , detected October 16, 1889, infesting 
sexual individuals of this species found on roots of the curled 
dock (Ruin ex crispus) at Champaign, 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 p in length by 15-18 p in width. 
They are nearly spherical to short ovoid, and often have a short 
truncate, or slightly papillate, base. The fatal disease character¬ 
ized by this fungus was generally distributed among the corn 
root lice iu 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 conta¬ 
gion to the corn leaf aphis ( A . maidis) resulted unsuccessfully. 
