ORCHARD PLANT LICE AND THEIR 
REMEDIES.* 
c. p. Gillette; and e. p. taylor. 
The plant lice that are commonly designated as "aphids” have very 
similar habits, structures, and remedies. These should be known and under¬ 
stood by the farmer and fruit grower who have to contend with them. 
Nearly all of these lice are rather easily destroyed when proper remedies 
are intelligently applied to them. Probably the plant lice here mentioned 
are the most serious orchard pests in Colorado at the present time. 
GENERAL STRUCTURE AND HABITS. 
All of the plant lice get their food by inserting a beak and sucking the 
sap of the plant. They never eat away the tissue of the leaf. 
Throughout the entire summer, from spring to about the first of Sep¬ 
tember, all of our plant lice that infest orchard trees, increase in numbers by 
giving birth to living young. If eggs are laid at all they are deposited by 
the last brood of females in the fall. From the fact that a single louse is 
usually able to give birth to from 75 to 150 young, and as they mature in 
about eight to ten days after being born, it will readily be seen that the 
plant lice are capable of increasing with wonderful rapidity. This accounts 
for the fact that the lice may nearly all be killed from a tree and that tree 
be very seriously infested with the lice again within a few weeks. Usually 
the last brood in the fall are about one half males and one half females. 
These females deposit the eggs that live over winter and the lice all di'-- 
We have an exception of this rule, however, in case of the woolly apple 
aphis which lives over winter as young or partly grown lice upon the trunk 
and branches, and in all stages of growth upon the roots of the trees. 
Plant louse eggs usually hatch in the spring a little before the leaf buds 
begin to open on the trees that they infest. These early lice hatching from 
the eggs are always wingless in the species mentioned in this bulletin, and 
are called stem-mothers. These stem-mothers mature in a short time, are 
all females, and begin giving birth to young lice which constitute the second 
brood. It'is seldom that the second brood of lice have more than a very 
few winged ones. The remainder of the life history of these lice will be 
given under the different species treated. 
*This bulletin is an abbreviated edition of Bulletin 133, “A Few Orchard 
Plant Lice,” by C. P. Gillette and E. P. Taylor, and is prepared to give the 
most important information needed by fruit growers. Bulletin 133 gives 
a much fuller account of the plant lice, and is illustrated by colored plates 
of some of the most important species. The technical matter, and that 
which does not relate to the economical side is omitted from this edition, 
which is intended to meet the needs of most people. 
Bulletin 133 will be sent on request made to the Director. 
