XV, 4 
Oshima: Formosan Termites 
347 
new colony, raising a number of workers and soldiers. It is 
possible, therefore, that in the case of a building infested by 
the winged forms, the damage may be extended year after year, 
in spite of the existence of the termite-proof concrete layer. 
The office of the Nippon Yusen Kaisha at Keelung, Formosa, 
which was built in 1915 (Plate X, fig. 1), is said to be a good 
example of the termite-proof construction. Nevertheless, in 
August, 1916, that is, only one year later, damage caused by 
termites was found on the second floor (Plate X, fig. 2). At 
that time there was no damage on the first floor; there was no 
connection between the nests constructed on the second floor and 
the ground ; the concrete layer on the ground level was perfect, 
having neither crack nor joint; many hyaline wings, which had 
been cast by the imagoes of Coptotermes formosanus, were found 
in the building; couples accompanied by young larvae were 
found in the brick walls, especially in wood bricks. Such being 
the case, there could be no doubt that the building had been 
infested by the winged form, which entered the house in the 
swarming season. 
The concrete layer on the ground level may be strong enough 
to prevent the pest that starts from the ground, but it is of no 
use in preventing the intrusion of the winged forms. Certainly, 
in Formosa, the percentage of the damage to buildings has de- 
creased since the new method of construction was adopted; but 
the present building construction is not absolutely termite proof, 
because it does not prevent the entrance of the winged forms. 
TESTS OF THE RELATIVE RESISTANCE OF NATIVE AND EXOTIC WOODS 
It is evident that the changes made in several parts of build- 
ings in Formosa are more or less effective in preventing the 
damage by Coptotermes formosanus; but, since it is almost 
impossible to prevent the entrance of the winged forms, an 
investigation to discover other methods of prevention becomes 
necessary. 
From an economic point of view it is hard to eliminate non- 
resistant timbers from building materials, especially in the 
case of Japanese buildings. Under such conditions the treat- 
ment of timbers so as to provide immunity from the attack of the 
termite is considered more important than the former method; 
because it is certain that the preventive measures, namely, con- 
structing the concrete layer, etc., become unnecessary if the 
nature of timbers can be so changed that they are absolutely 
immune from the attack of the termite. 
