Aphids Injurious to Orchard Fruits, Etc. 17 
THE LONG-BEAKED THISTLE APHIS.! 
In some localities the long-beaked thistle aphis is abundant on 
plum trees. In structure this species most closely resembles the 
rusty plum aphis. The insects are shiny green and black, some of 
the wingless ones and all of the winged ones having a large black 
patch on the abdomen. (Fig. 10.) 
Although this species becomes very abundant on the trees, it does 
not curl the leaves to any extent. Trees have been observed in the 
vicinity of Washington with the underside of nearly every leaf 
thickly covered with the insects, and yet these leaves were rolled 
only slightly from the edges. 
The insects always feed on 
the underside of the leaves 
or on the very tender twigs. 
Practically all the injury 
done to the trees is by the 
spring forms, the fall mi- 
grants being scattered. 
SEASONAL HISTORY. 
The eggs of this species 
are laid upon the plum, as 
are those of the rusty plum 
aphis. In the early spring 
the stem-mother he tches 
and gives birth to -iving 
young. Winged forms de- 
gin to appear as early as 
the second generation and 
continue to be produced  !s. 10—The long-beaked thistle aphis: a, Wingless fe- 
il midsumm Thes male; b, antenna of spring migrant; c, antenna of fall 
until mids er. ese migrant; d, cornicle of fall migrant; e, cornicle of spring 
migrate to thistles, where migrant; f, cornicle of stem mother; g, cornicle of egg-lay- 
. ing female; h, cornicle of male. «a, Much enlarged; b-h, 
they produce the first of  moreentarged. 
the summer forms. After 
having produced numerous generations on the thistle during the 
summer, fall migrants are produced which return to the plum trees 
to deposit the young egg-laying females. These, after being fertil- 
ized by the males, lay the winter eggs. 
THE WATER-LILY APHIS.’ 
Plum trees are sometimes thickly infested by an aphid with swol- 
len honey tubes, the water-lily aphis. The insects are brownish, the 
winged forms having a black head and body. 
1 Anuraphis cardui (L.). 2 Rhopalosiphum nymphaeae (L.). 
166596°—20—Bull. 1128 
9 
3) 
