Daily Kennebec journal. [microfilm reel] (Augusta, Me.) 1870-1975, 1915-10-20

plantlice as these insects are common
| ly called. 1t is Of economic importance
that the complete life history of a pest
should be known in order that the most
! favorable method of combating it may
| be selected.
| One of the most troublesome of our
plum insects in Maine is a species of
plant louise inhabiting the shoots and
the ventral surface Of the leaves, or
dinarily without causing curl or sim
liar reformation of the leaf, but eXhib-
| iting a dangerous tendency to feed also
upon the young fruit itself as we'll as
tapping the fruit stems.
| After sucking the sap from the fresh
leaves in the spring and injuring the
kgreen fruit while it is still small; these
| insects, the first generations of which
are without wings. produce winged
generation that takes flight from the
plum and the insect is not seen upon
that tree again until fall.
| Where this aphid spends the sum
mer has been a mystery which has
| until this season been unexplained. The
clue to the situation was found in the
fact that this insect is covered beneath
! by light waxy powder which seemed
to have no significance in the career Of
a leaf feeding aphid. This led to a
comparison of the plum pest with a
species found upon certain water
plants and fitted for it's semiaquatic
| life by a coating of waxy powder upon
| the lower surface of its body.
Surprising as it may seem a mic
roscopic examination did not reveal
any structural differences between the
aphid feeding on the plum in spring
and that living during the summer
on arrowhead and other aquatic
plants. So this spring the migration
test" was made by placing the spring
migrants (alate Vviparous forms) from
plum upon water plantain, arrowhead,
and cat-tail flag, which had been pot
ted and kept under laboratory con-
ttrol. The plum migrants accepted
them all readily, and their progeny
were perfectly content with the habi-
tat given them.
Thus the strange life cycle of the
aphid is found to include a residence
upon the plum, migrating thence to
water plants for the summer and re-
turning to the plum in the fall for the
deposition of the overwintering egg
which provides for it's spring genera
tons upon that tree. There is, per-
haps, no bird migration more remark
able than the fight of a migratory
aphid and the histories of many species
OF this family of insects have the thrill
Of a dramatic tale Of adventure.
I The plant louise by leaving one kind
Of vegetation and seeking one entirely
different escapes many of its natural
enemies and finds fresh feeding ground.
Often a practical control measure is
suggested by the facts Of the complete
life cycle when they are known. In
! the present case II might be possible
to escape all trouble with this injuri-
GUS plum aphid by draining some
neighboring pool which harbors the
plants necessary for its life in sum-
inner. thus starving it out and getting
rid OF 1t permanently.
| It would of course. depend upon local
circumstances as to whether such a
proceeding would be practicable II
the elimination of the summer food
plants cannot be accomplished. the di-
trect method OF applying contact sprays
| to infested trees each spring will need
to be considered by the people trying
to raise plums in Maine
CHAS. D. WOODS,
Director.