13 
information in Bulletins 10 and 25, of his station, both as to the life 
history and known remedies. Mr. Washburn kindly advised me as to 
the best locality in which to carry on the experiments and also furnished 
me with a list of hop-growers. Aurora was selected as a central point 
for operations. The season was very backward when IJ arrived there on 
the 26th, the plum trees only just coming into blossom, and for the pre- 
ceding five weeks there had been more or less rain daily. 
The most important point was to ascertain if other plants or trees 
than Plum and Prune existed upon which the winter eggs are deposited, 
and all plants were consequently examined during the whole time of 
my work up to June 25. In no instance could the lice be found on any 
other than the plants mentioned. A Phorodon feeding upon mint is 
without doubt a distinct species, as it could not be induced to feed 
upon the hop vines, and its migrant has been observed to leave its. off- 
spring upon the mint. 
With the exception of seedling plums, upon which the stem mother 
was found, no other wild plums were met with, and upon all the wild 
cherries examined, both in Oregon and Washington, no trace of the Hop 
Louse could befound. It was not until May 12 that the first colonies of 
Phorodon humuli were met with upon various plum and prune trees, the 
stem mothers with their offspring chiefly, yet in some instances young 
of the third generation. As late as May 23 stem mothers with but few 
young were found, and on May 26 the first winged migrant was observed. 
With the beginning of June the winged insects could be found almost 
anywhere, yet not in large numbers, and a week later the young of this. 
generation could be found occasionally upon the hop vines. This has 
been an unusually late season, and in ordinary years the lice may be 
expected to appear upon the vines about three weeks earlier. 
The Hop Louse has been, generally speaking, not numerous, while 
the predaceous insects have been very abundant, so much so that in the 
early spring in some of the yards before they were plowed, from fifty to 
seventy-five lady-birds could be counted to every hill. These were 
attacking two species of Aphidids, which occurred on weeds, and to 
some extent on the hop vines, which they speedily cleared of lice and 
had to leave in search of food elsewhere. The more numerous of these 
lady-birds, numbered 8, 4, 5, 3, 2, 7, 11, and 14, following the order of 
their abundance, I have forwarded for determination.* No. 14 was 
always present whenever hop lice occurred. Many of the colonies of 
Phorodon under observation upon plum trees were entirely destroyed 
by these lady-birds, and chiefly by No. 8, which is a most active little 
insect. Other predaceous insects, such as Syrphide and Chrysopa, 
were also present in large numbers, and onone occasion upon plums. A 
*The Coceinellids sent by Mr. Koebele represent the following species: 8, Adalia 
frigida, var. barda; 4, Hippodamia spuria ; 5, H. parenthesis ; 3, H. 13-maculata; 2, 
Coccinella transversoguttata and its var., transversalia ; 7, Harmonia 14-guttata, var. 
cardisce; 11, H. 12-maculata; 14, Scymnus nebulosus.—Eds. 
