December, ’20] SPULER: WINTERKILLING OF SAN JOS£ SCALE 443 
Chairman A. L. Melander: The next paper is entitled, “ Winter- 
killing of the San Jose Scale.” 
WINTERKILLING OF THE SAN JOSE SCALE 
By Anthony Spuler, Washington State College 
Since early in the spring there has been considerable evidence to 
lead the fruit grower to believe that the San Jose Scale had been killed 
in large numbers during the past winter. The usual method of scraping 
the bark of badly infested trees with a knife showed that the insects 
were not juicy as commonly found at this time, but that they were 
dry and came off readily. 
In order to determine to what extent the scale had been killed, a 
thorough examination of their overwintering condition was made. 
Early in March the district horticulture inspectors sent in infested 
branches from a number of orchards in each of the fruit-growing 
sections of the state. This was followed a little later by a personal 
investigation in the field in which all of the fruit-growing sections were 
visited. Samples were cut from healthy trees in a number of orchards 
within a district. Every effort was made to secure material that was 
typical for the various localities visited. The material secured in this 
way was carefully examined. Thousands of individual insects were 
dissected off under a binocular and their condition noted. It was 
possible in this way to learn the per cent of San Jose Scale still alive. 
Following are the results obtained: 
Locality 
Total 
Counted 
Dead 
Alive 
Per 
cent 
Alive 
Clarkston. 
. 10,144 
9,595 
549 
5.4 
Walla Walla. 
. 12,816 
12,388 
428 
3.2 
Prosser. .. 
. 2,545 
2,545 
0 
0 
Yakima. 
. 8,595 
8,526 
72 
1.5 
White Salmon. 
. 2,093 
1,729 
364 
17.8 
Wenatchee. 
. 5,409 
5,309 
100 
1.8 
Spokane. 
. 2,485 
2,013 
472 
19.2 
In contrast to the foregoing is the aterage per cent of winterkill of 
the San Jose Scale for the past ten years, not including the winter of 
1919-20 for the following localities: Clarkston, 19 per cent; Walla 
Walla, 24 per cent; Yakima, 32 per cent and Wenatchee, 40 per cent. 
The high percentage of winterkill of the scale might be explained in 
two ways. In the first place the winter started rather early. In Octo¬ 
ber the temperature in the fruit-growing sections dropped as low as 
12 to 14 degrees Fahrenheit. This was in all probability before the 
scale had gone into hibernation and before they were in a condition to 
