42 THE COLORADO EXPERIMENT STATION 
Specially upon the red or Americana plums. Throughout the sea¬ 
son it seems to have a strong tendency to cluster upon the bark 
of tlie ten derest new growth. 
The louse is nearly always accompanied by ants, that attend 
it for the honey dew that is secreted. Usually in the colonies a 
few larvae of one of the small black Coccinellids (Scymnus sp.) 
can be seen. They are recognized at once by the white secretion 
that covers their bodies. 
This louse remains upon the plum throughout the entire year. 
We have found it in many places east of the mountains both in the 
vicinity of Fort Collins and in the Arkansas Valley, but we have 
not taken it on the western slope. It often becomes abundant 
enough to be a very serious pest, but on account of its body being 
entirely free from any powdery secretions, it is readily treated and 
destroyed. From about the first of August on through the summer 
we have also found this louse upon barnyard grass {Bchinochloa 
Crus-gain.) The louse becomes darker in color late in the season and 
the oviparious female in the fall is almost black. The small winged 
males are black in color. The egg-laying females are wingless 
and, in the laboratory, Mr. Bragg succeeded in getting them to lay 
eggs quite freely upon plum twigs, but he was unable to find any of 
the eggs upon infested plum trees out of doors. The lice upon 
plum trees during September and October were all apterous except 
the males, but whenever found upon barnyard grass there were 
many winged individuals present that seemed to be fall migrants. 
Mr. J. T. Monell* reported this louse upon Panicum proli- 
ferum) in Missouri, and Professor O. W. Oestiund** reports it 
upon fox-tail (Setaria glaiica), barnyard grass {Bchinochloa Crits- 
galli) and Virginia Creeper (Ampelopsis quinqiiefolia in 
'Minnesota. 
REMEDIES 
The remedies for this louse are the same as for the green 
apple aphis, without the early treatments for the destruction of 
eggs. 
THE BLACK CHERRY LOUSE 
{Myzus cerasi Fab.) 
Plate II, Figs, i, 2, 3, 4. 
This is an insect that has long been known in Europe and for 
more than half a century, at least, has been a pest upon cultivated 
cherries in the eastern portion of this country. It is generally dis¬ 
tributed through the orchards of the eastern slope of the Rocky 
Mountains in Colorado and has found its wav into a few orchards, 
* Bull. 5, U. S. Geol. Survey, p. 23, 1878. 
** Aphids of Minn., p. 67, 1887. 
