June, ’23 
HOUSER: DUSTING TALL TREES 
247 
sphinx. In the two areas mentioned where it was not possible to secure 
a perfect application some caterpillars survived but these were not 
numerous enough to restock the grove for subsequent broods. 
Some Defects of the Airplane Method of Dusting 
As might be expected, with the seasons additional experience some 
defects in the general proposition of treating tall trees by airplane and in 
particular of the specific equipment which we used in the work have be¬ 
come apparent. 
A general criticism which might be made of the proposition of air¬ 
plane dusting as a whole is that it is difficult to determine the extent of 
the area covered by any single passage of the dusting plane, particularly 
when one is operating on a large woodland. It is hard to designate or 
mark the treated area so that spaces may not be missed or be double 
treated with the next passage of the plane. 
This trouble would be at least partly and probably largely overcome 
if certain changes were made in the apparatus. As the installation is 
now constituted the complete attention of two men is required to liberate 
the dust. Had the man in the passenger cockpit any time to look 
about it is doubtful if he could see much because of the dense cloud of 
dust with which he is enveloped when the mechanism is in operation. 
If the distributing machinery could be driven by an electric or wind 
motor, the hopper centrally installed and the dust cloud released at the 
rudder rather than at the side of the cockpit, the vision of the observer 
would not be interferred with and he would be left free to note the dis¬ 
tribution of the dust over the area under treatment. 
It has been suggested to the writer that perhaps one man could 
pilot the plane and at the same time operate the liberating apparatus if 
such was mechanically driven but in this I do not agree. In my opinion 
the entire attention of the pilot is required in flying the ship just as low to 
the tree-tops as is possible—that the success of the operation depends 
upon at least moderately low flying and that the services of a second 
man are essential for operating the distributor and observing the area 
covered by the dust. The latter cannot be estimated, neither can it be 
observed from the ground in large wooded areas, and since distribution 
can be noted from the air only, it follows that either an observer must be 
in the dusting plane or a second plane must be used for observation 
purposes. Of the two plans, obviously the most practical is the first 
named. 
Another criticism of the method may be made justly that appropriate 
