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providing for themselves and their charges a ready means of escape from 
confinement, as well as a passageway for the possible introduction of 
q other plant lice from without. July 25 and 30 two other hills were 
opened and found unchanged. From a fourth hill, examined August 2, 
: and a fifth, opened September 2, everything had escaped, neither ants 
nor plant lice remaining; while the sixth, opened September 11, con- 
tained an abundance of the root aphis (winged adults and young) as well 
4 as the usual ants. In all ihese cases a critical examination of the en- 
tire plant above ground showed beyond question the absence of the aérial 
aphis. 
In the large breeding cage near the insectary, corn was planted 
early in May, 1890, and the hills were stocked June 3 and 4 with aunts, 
ant larvee, and root lice, others being added to the original stock June 
13, July 1, 10, and 16, August 2 and 18, and September 15. ‘These re- 
peated additions were made necessary by the gradual disappearance of 
the root lice from the plants, which did not thrive perfectly at first, ow- 
ing apparently to the shade of the screen. No aérial lice appeared in this 
cage at any time during the progress of the experiment. This was termi- 
nated October 5, at which time root lice were still present on the corn. 
In another experiment, made June 16, 1891, by transferring the 
same species to hills of planted corn in the enclosure above described, the 
same results appeared. Root lice were reared on all the hills through- 
out the entire summer, but there was no appearance of aérial hce at 
any time up to September 16, when the experiment closed. 
In 1891 both corn and sorghum were grown in this enclosure for 
experiment, and the plants were first stocked June 16. Additional speci- 
mens of both the root aphis and the small brown ant were introduced 
June 27 and 29 and July 17, and ants alone, including their pupe, lar- 
ve, and eggs, July 24. By exposing single roots in little cavities in the 
earth and covering these with glass, it was easy to watch the behavior of 
the insects after they had been put in place, and it was thus learned that 
the sorghum hills were deserted almost at once. Consequently no root 
lice were found on the sorghum roots when the plants were dug up July 
13 and September 16. On the corn, however, the root aphis continued 
until the experiment was closed at the date last mentioned, but no 
aérial lice appeared at any time on either kind of plant. 
Another smaller experiment was tried with a hill of sorghum only, 
transplanted to a box July 3, stocked with the root aphis and with ants 
: of all stages, and covered with Swiss muslin. July 10 and August 1 
j more root lice were added, and July 17 both lice and ants. Ants were 
observed at work in this enclosure July 11; 18, 20, 22, and 30, August 
5, 7, 10, 15, and 18, and September 1 and 16; but no aérial corn lice 
appeared at any time, and no corn root lice were seen after August. 5. 
August 18 the common yellow sorghum louse (Chaitophorus flavus) 
had become abundant on stalks and leaves of the plant in the cage with 
the ants, and this condition of things continued until September 16, 
when the experiment was dropped. Apart from the negative result 
of this attempt to bring the corn leaf aphis out of the root louse, we 
get additional evidence that the latter does not thrive on the sorghum 
root. 
