THE MIGRATORY APHID AND THE 
LANDSCAPE GARDENER 
EDITH M. PATCH 
State Entomologist, Maine 
Strange Partnership of the Alder and Soft Maple as Alternating Hosts of a Pest That Disfigures One of Our 
Most Popular Shade d rees, Which Gives Two Opportunities for Winter Control by Spraying and Cleaning 
YOU not think a Cut-leaved Maple would feature well 
fegpfl at the left of that opening?” asked Mr. Countryman of 
w fJr .r, Mr. Landscape Gardener. 
g ffsrefc D “Yes,” replied Mr. L. Gardener cordially, “the 
Maple would grow into that vista very well, and be an orna- 
ment, too, if it were not for your Alders.” 
Mr. Countryman frowned. The Alders lined the stream 
the other side of a little hill and were not in sight from where 
the men were standing. In fact, the proposed Maple and 
the Alder fringe could not be seen at the same time from 
any spot except the top of the rise. Besides, suppose they 
could? What was there inharmonious in a landscape har- 
boring both these trees if they were placed in a becoming 
setting? 
He had requested that a capable man be sent to him, both 
practical and aesthetic, and the candidate was telling him not 
to plant a Maple because there were Alders off somewhere the 
other side of a hill! 
Mr. Countryman turned, his frown deepened by these reflec- 
tions, to take a keen look at his adviser. He had not previously 
noticed that he seemed stupid. 
Mr. Gardener met the glance with a frank smile. “If you 
will walk over to those rocks with me,” he said, “I’ll 
tell you what 1 mean.” 
A few rods brought them to the spot indicated 
where there was a clump of native Silver Maples. 
“ What is the matter with those leaves?” 
asked Mr. Countryman, sharply, as 
they paused beside the trees. 
Mr. Gardener pulled down a lowbranch. 
The usually graceful leaves were drawn 
and saggy and thickly lined beneath with 
a mass of some substance that looked 
like a tangle of sticky white threads. 
Poking into this, they found hidden un- 
der it numbersof small dark bodied insects, 
some already with wings and others with 
swollen “shoulders” indicating that they 
had not long towaitforthe means of flight. 
“ These are aphids,” 
explained Mr. Gar- 
dener, “ about ready 
for their migration . 
The damage to the 
Maples is already 
done. These leaves 
tapped of their sap, 
will not regain a 
healthy appearance 
all summer.” 
They continued their 
walk, and Mr. Coun- 
tryman noticed with 
increasinginterest that 
he was being led to 
the Alder fringe. 
“ Phis is thedestina- 
tion of the migrants 
from the Maple 
leaves,” said Mr. Gardener as they stopped a second time. 
“ Flying to the Alder, they come to rest on the underside of 
the leaves and there produce the young which go to the stem 
and make the fluff covered colonies which are sometimes known 
as alder blight.” 
Mr. Countryman’s frown appeared again. “This is late 
June,” he said, tersely. “The ‘migrants’ are just leaving the 
Maples. Alder blight has been present on these bushes since 
early May.” 
“Yes,” responded Mr. Gardener, quietly, “I was about to 
mention the fact that this aphid has one of those life histories 
complicated by two methods of wintering over. One is in the 
egg on the Maple from which hatches the first spring generation 
on that tree, and the other is the hibernating young produced 
on the Alder in the fall and lurking under the fallen leaves until 
spring. It is these over-wintering young which begin to feed 
on the Alder early in the spring and start colonies that are aug- 
mented later by their sisters from the Maple. Winter sprays 
on the Maple and clearing up the refuse about the Alder will 
help to control the aphid, however.” 
Mr. Countryman laughed. “You make me want to take up 
entomology for a pastime just for the fun of knowing stories 
like that.” 
“ Improbable, but true, as some one has put it,” returned 
Mr. Gardener with a smile. 
“The Cut-leaved Maple is a cultivated variety of the 
native Silver Maple,” he continued. “ They 
are the same species and susceptible to the 
same insect attacks.” 
Mr. Countryman nodded. “1 get your 
point, at last,” he said. 
Then he asked: “ But can’t this migra- 
tion be prevented? These Alders, purple 
stemmed in the winter and spring, are the 
making of this outlook, and I’d my heart 
set on a Cut-leaved Maple.” 
“Well,” returned the other, “in a local- 
ity like this where the Alders are in a 
restricted area — your farmer neighbors 
keeping theirs cut 
down for pasture rea- 
sons — I do not seewhy 
you could not get rid 
of the Alder blight 
during the summer by 
the simple process of 
wiping and crushing 
the conspicuous colo- 
nies from the stems. 
In that case there 
would be no fall mi- 
gration to the Maple 
and therefore no leaf 
trouble there in the 
spring.” 
“Ah-h,” was Mr. 
Countryman’s com- 
ment. His frown had 
disappeared. 
THE APHID HAS TAKEN POSSESSION 
The aggressive quality of this blight (Prociphibus tesselata) is abundantly evident. 
The Maple leaf (photographed July 26th) shows the havoc wrought by the spring 
forms before their migration to the unfortunate Alder, upon which the summer 
colonies prey. (Branch of Alder photographed Sept. 1st) 
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