396 YEARBOOK OF THE DEPARTMENT OF AGRICULTURE. 



A moist condition of lumber and square timber, such as results from 

 close or solid piles with the bottom layers on the ground, or on a 

 foundation of old decaying logs, or near decaying stumps and logs, 

 offers especially favorable conditions for the attack of white ants. 



.SEASONED PRODUCTS IN THE ROUGH. 



DRY LUMBER. Dry lumber in stacks or storage is liable to injury 

 by powder post borers (fig. 50). The conditions favoring attack are: 

 (1) The presence of a large proportion of sapwood, as in hickory, 

 ash, and similar woods; (2) material which is two or more years old or 

 that which has been kept in one place for a long time; (3) access to 

 old infested material. Therefore such lumber should be frequently 

 examined for evidence of the presence of these insects. This is always 

 indicated by fine flour-like powder on or beneath the piles, or otherwise 

 associated with such material. All infested material should be at once 

 removed and the infested parts destroyed b}^ burning. 



DRY COOPERAGE, WAGON, AND HANDLE STOCK. These are especially 

 liable to attack and serious injury by powder post borers (fig. 50), 

 under the same or similar conditions as in the case of drv lumber. 



FINISHED OR UTILIZED PRODUCTS. 



TIMBERS AND OTHER WOODWORK IN NEW AND OLD BUILDINGS. 

 These are often injured by powder post borers (fig. 50), or white ants 

 (fig. 52). If by the former in new structures, it indicates that infested 

 material was used in the structure and that after being thus intro-, 

 duced the insects continued to breed and extend the injuries, regard- 

 less of paint -and varnish or other external treatment which would 

 otherwise prevent attack. If the trouble occurs in old buildings it is' 

 usually due to a large proportion of sapwood in the frame timbers, 

 flooring, and other parts, which, owing to the age of such material, 

 is rendered especially attractive to certain classes of powder post 

 borers. After such wood is once infested, the insects continue to 

 breed and extend their work for many years, or until all the sapwood 

 is converted into powder. Figure 51 illustrates an example of pine 

 flooring in an old barn which was damaged by one species of this class 

 of insects. 



The conditions in new or old buildings favorable for attack by white 

 ants (fig. 52) are decayed or moist wood in the underpinning and fouin 

 dation timbers which are near the ground, or the location of buildings 

 in the vicinity of decaying wood of any kind in which the insects are 

 breeding. After a building is once infested, however, the destructive 

 work is extended into sound and dry wood. Old logs and stumps are 

 favorite breeding places for these insects, from which they may travel 

 or fly to a considerable distance to reach suitable places to extend 



