28 
THE COEORADO EXPERIMENT STATION 
Black Leaf, 3 per cent strength. 
Black Leaf, 2 1-2 per cent strength (a little weak. ) 
THE CLOVER APHIS 
{Aphis bakeri Co wen) 
Plate III, Figs. I, 2. 
This louse was described by Mr. Cowen in Bull. 31 of this 
station in 1895. Aphis cephalicola Cowen, described from heads of 
white clover, is the same species. 
On April 13, of this year we found a red-stem-mother of some 
unknwn aphis rather common, and in many cases fully grown, up¬ 
on the buds of apple and pear trees about Delta, Colorado. The 
color varied from a dark green streaked and mottled with red to 
a deep dark red, with cornicles very short and pale yellow through¬ 
out. At this time the apple buds were just beginning to open and 
peach trees were nearly in full bloom. It seems probable that these 
stem-mothers must have hatched fully two weeks prior to this date 
to have become fully grown. The green apple aphis {A. ponii) 
at this time was just hatching and none were found that were more 
tlian half grown. 
The identity of the louse was not suspected until the depart¬ 
ment artist. Miss M. A. Palmer, suggested that the second brood 
lice looked like her drawings of the clover louse, A. bakeri. A 
careful comparison indicated that the two forms were identical 
except for a little difference in color. This second generation (the 
offspring of the stem mothers) were light green or yellowish green 
in color, while bakeri, upon clover, is pink or yellowish. A large 
pale orange blotch surrounding each cornicle is also quite char¬ 
acteristic. Sprigs of apple infested with this louse were put in a 
cage with red clover and the lice in all stages readily adopted the 
clover as their food plant. Later the pink form was also found 
upon apple and crabapple {Crateg^ls sp.) and no doubt was left 
that all were one species with varations in color. 
EOOD PLANTS AND LIEE HISTORY 
Summing up the life habits of this insect from all the observa¬ 
tions we have upon it in the records of the Experiment Station 
for the past nine years we conclude as follows: 
The clover aphis, A. bakeri, infests the cultivated and sweet 
clovers and alfalfa throughout the warmer part of the year where, 
apparently, it never occurs in the oviparious form nor as eggs. In 
the fall, a portion of the winged lice migrate to apple and pear 
trees where eggs* are deposited to live over winter and hatch into 
the red stem mothers the following spring*. The descendants of 
* Oviparous females and eg-gs we have not seen with certainty. 
