June, ’23 
HOUSER: DUSTING TALL TREES 
243 
with plantings of ferns, wild flowers, rhododendrons and other shrubs, a 
studied effort having been made to preserve the natural effect, rather 
than create an artificial atmosphere. The result is most pleasing and at 
the same time it had been made almost impossible to use liquid machines 
without doing serious damage by trampling the low growing plants. 
The infestation of canker worm larvae was only moderately severe. 
In no part of the woodland in which we operated were the insects 
sufficiently plentiful to cause defoliation, though it is no uncommon 
thing in northern Ohio for woodlands to be stripped by this insect. 
There were, however, enough caterpillars to cause considerable mutila¬ 
tion of the leaves of the more susceptible species, such as, elms, linden 
and maple and thus furnish a fair basis for the experiment. 
Object of the Test 
The more important points under consideration in this test were as 
follows:— 
1. To determine if cankerworms can be controlled successfully by 
dusting. 
2. To determine whether the dust released above a dense woodland 
will penetrate through the foliage of the tree crowns to the undergrowth 
beneath, as well as to determine the degree to which the dust may be 
controlled when so applied. 
3. To secure such data as possible pertaining to the general prac¬ 
ticability and defects of this method of forest insect control. 
Details of Applying the Dust 
The Postal Landing Station and Hangars at the Glen Martin Field, 
some four miles distant from the Severance tract, were used as a base of 
operations. 
On the afternoon of May 23, Lieut. Macready made a careful ground 
inspection of the woodland to be treated, and in passing it may be said 
that while a ground inspection previous to the act of application may not 
be essential, it undoubtedly is of considerable value to the pilot later on. 
During the forenoon of the following day, May 24, approximately 
325 lbs. of powder was distributed over the woodland. The meter- 
ological conditions were not very favorable, the chief unsatisfactory 
factor being a wind which not only changed direction occasionally but 
in velocity as well, the latter averaging about 12 to 15 miles per hour. 
This is too high when operating over an area as small as 30 acres. 
For the most part the plane flew crosswise of the wind in order to 
