The European Elm Scale 21 



there were 333. Small branches and twigs, green and sound, but of 

 low vitality were chosen for the count. The bark was smooth, with 

 little or no cork present ; it was coated, even incrusted with lime-sul- 

 phur. Scales counted as living were plump, full of normal body 

 fluids, and of the usual color. Those shrunken and discolored or dried 

 were counted as dead. Owing to the height of these elms the tops were 

 reached with difficulty, if at all. They were not washed down later 

 in the summer with the garden hose. 



They stood the summer of 1907 well and seemed the better for the 

 application, but did not make so good a growth nor jo prompt a recov- 

 ery from the injuries of the preceding year as the other elms which 

 had been both sprayed and washed. An American Elm of about the 

 same height and age, growing in the same row was not sprayed, but 

 was used as a check tree. It was rather more seriously infested than 

 the others and died late in the following summer. Counts of three 

 thousand dead and living scales from the check tree made at the same 

 time as the counts from the sprayed trees showed that on it about ten 

 per cent of the scales were dead. 



A Brief Summary and Some Inferences 

 (lime-sulphub) 



It is not generally profitable to draw general conclusions from the 

 results of a single experiment or from the experiments of a single sea- 

 son ; still from the results of the experiments detailed in the foregoing 

 pages it seems safe to infer : 



1. That in every instance many of the hibernating larvae escaped 

 destruction by the lime-sulphur; some because they were not suffic- 

 iently affected by it, others because they were concealed in the semi- 

 cocoons of the female insects or protected by projecting ridges of cork, 

 or hidden in deep crevices in the bark. 



2. Before spraying with lime-sulphur it would be well to wash 

 away from the bark all visible clusters of dead females in order to 

 destroy the winter larvae concealed within and around them. 



3. After spraying in the winter with lime-sulphur, the trees 

 should be washed down with a stiff stream of water under high pres- 

 sure late in May or early in June to destroy the living female insects 

 which escaped the action of the insecticide. 



Some Questions and a Bit of Discussion 



In the last few pages I have given a brief account of the methods 

 used in the vicinity Of Reno, Nevada, in 1907 to check the European 

 Elm Scale. Those who realize that even within a limited area the com- 



