4 
The reasons why the species has become so conspicuous a pest are 
threefold: First. because of its ravages to a crop hitherto little troubled 
by insect attack, if we except the pea weevil, which has always been 
present in gardens and fields for upwards of a century and has come to 
be looked upon as anecessary evil; second, because it is a species never 
before noticed, so far as records go, as having been destructive to peas 
in this country; third, because of the great difficulty that has been 
experienced in its treatment, pea growers during the first year of its 
ravages having met with almost complete failure in the remedial meas- 
ures applied. 
Although garden and field peas are the crops most injured by this 
aphis, sweet peas, red and crimson clover, as well as vetches and tares! 
are affected, and in some cases have been damaged. Attack begins on 
the young pea vines; the “‘lice’’ gather in clusters at first under and 
within the terminals, and as the leaves become covered they attack also 
the stems, and by their numbers and voracity sap the life of the plant. 
Whole areas of vines are frequently seen covered with the aphides, 
which in a very few weeks are able to destroy acrop. Attack is seldom 
noticed until May? in the more southern States in which the insect is 
found, and a little later in its more northern range. 
The complete life history of this species is not known, but like other 
aphides it produces many generations each year. 
According to present knowledge, the pea aphis hibernates chiefly on 
clover, particularly crimson clover, from Delaware southward. In the 
District of Columbia it winters also on vetch. From these plants the 
‘lice’? spread by flight in April and May to peas, which they attack 
while the vines are young. 
_As with other aphides, the females at certain periods produce living 
young. They attain maturity in from ten to fifteen days, and possibly 
in less time in the hottest weather. Young that were born March 4 
reached maturity (winged form) March 16, or twelve days from the 
time of birth, and reproduced young three days later. 
As an instance of the rapid reproductive powers of this insect, 
Professor Johnson’s estimate is interesting. He found that females 
produce from 110 to 120 young and that in one case where aphides 
were observed on the first of May the fields were abandoned on account 
of ravages three weeks later. Calculating from the average number of 
1A considerable number of alternate food plants has been observed for 
Macrosiphum pist in Europe. 
2In 1901 Mr. Samuel R. Haynes, Portsmouth, Va., reported the presence of 
this species in that locality about April 7. During the second week of May the 
writer found it numerous on crimson clover and vetches at Washington, D. C., 
and May 14 it was reported at work upon peas in the District of Columbia, near 
the Maryland State line. 
A6——49 
