67 
among its food plants many weeds of diverse families. The more 
important of its food plants are red clover, crimson clover, field 
pea, sweet pea, vetches (known also as "tares"), beet, lettuce, shep- 
herd's purse, and nettle, not to mention the rest of the weeds. Alfalfa 
seems to be immune from attack. Thirty sweeps of the net in red 
clover yielded 3000 of the aphids, while the same number of similar 
sweeps in an adjoining field of alfalfa gave only 30. This alfalfa 
was mixed with som^e clover, however, and observations on the few 
lice that could be found on the alfalfa failed to find them in the act 
of feeding. On soy-beans growing next to heavily infested clover, 
not a single louse was found. Where crimson clover is grown, the 
aphid prefers it to red clover, it is said. 
Where peas are grown, the aphid winters in a field of clover or 
on weeds (as a wingless female or as an egg), and in spring is con- 
fined to these until the peas start to grow, and then it does not get 
to the early varieties, tho it devastates the late-sown peas. In early 
spring most of the aphids are wingless and remain where they happen 
to be, but in late spring (May 1, Delaware) and early summer there 
are many winged females that can go frorn clover to peas and start an 
infestation. The first aphids select the youngest leaves and shoots, but 
eventually the lice cover the entire plant and sap out its life, rendering 
it unfit even for fodder. 
In Wisconsin the louse was noticed in a five-hundred acre field of 
peas about July 20; in less than a week all the plants were dead and 
brown. In Maryland in 1899, the louse destroyed peas valued at 
$3,000,000, conservatively estimated, and in 1900, $4,000,000 worth 
were destroyed. 
On red clover, the youngest leaves and stems are the first to be 
attacked, and these wither and die if many aphids are present. Wilted 
leaves mark the spread of the pest over the plant. Red clover, how- 
ever, can stand a good deal of this injury, and if a heavy rain happens 
to occur when the plant is covered with the lice, they are washed off, 
and the field is safe for the rest of the season. There are also numer- 
ous insect enemies and a fungous disease, which kill off immense num- 
bers of the lice. At times a combination of circumstances occurs, how- 
ever, under which the plant is killed, root and all. The natural checks 
upon the increase of the aphid may be insufficient; but dry weather 
seems to be the most important factor. Without rain the plant can 
not replace the sap taken by the aphids, let alone make any growth; in 
dry weather the fungus can not develop ; and in the absence of heavy 
rains to wash them off the plants, the aphids thrive. In dry weather, 
when the plants are loaded with lice, the cutting of the clover is the 
last straw. 
In 1903 the louse killed an immense amount of red clover, and 
weakened much more, in De Kalb county. Being sent there by the 
State Entomologist, I found on the farm of Mr. A. E. Myers, at Mill- 
brook, August 19, eighty acres of dead clover roots in one field. Not 
one root in a thousand showed any signs of life, and on the ground 
were thousands of the cast skins of the aphid. At cutting, the lice had 
