TERMITES IN THE UNITED STATES. 15 



However, the annual emergence of the winged adult termites is an 

 indication of infestation and the point of emergence shows the ap- 

 proximate location of the infested timber. The presence of the 

 earthlike tubes on timber or rock foundations of buildings is also a 

 warning that the building is infested by termites. 



While injury by termites in tropical regions affects not only the 

 soundness of the building, 1 but the dry, hard wood of furniture and 

 other contents as well, in this country attack is usually begun in moist 

 or decaying foundation timbers. However, termites are able to ex- 

 tend their burrows throughout dry, hard wood and other dry sub- 

 stances, provided that there is access to moisture elsewhere; i. e., 

 they make use of a mixture of moist frass and earth in creating more 

 favorable conditions. Thus there is, in infested buildings, occasional 

 damage to flooring, wooden partition walls, wainscoting, molding, 

 door casing (PL IV, fig. 2), sills, window and door frames, wooden 

 lath and wall plaster, 2 as well as to tiling o rother interior construc- 

 tion made of wood pulp (PI. V), furniture, wall paper, starched 

 cotton curtains, and various stored material. 



In infested buildings, where they have worked for several years, 

 the insects having usually entered the house by means of joists or 

 stringers in contact with the ground or set in concrete, work is begun 

 in the flooring next to the walls, and burrows are excavated in toward 

 the center of the room. The woodwork of coal bins in cellars some- 

 times becomes infested and is the cause of the insects gaining entrance 

 to the flooring and other woodwork of the building. 



Flooring, other woodwork, and furniture in infested buildings 

 above boilers or furnaces where the temperature is high or the wood 

 is moistened by hot steam are especially liable to attack. 



In addition to the private residences, hotels, and business houses 

 occupied by man, termites infest factories, granaries, barns, green- 

 houses, sheds, outhouses, and other wooden structures. The frame- 

 work of wooden greenhouses, which are always warm and moist, is 

 especially liable to attack and may be seriously damaged. The in- 

 jury in these structures is extended to the wooden plant benches, 

 plant tubs, label sticks, and sometimes to the growing plants. 



Many other structures of wood are damaged by termites, any tim- 

 ber in contact with the ground being especially liable to attack. 



1 Calotermes marginipennis Latr., recorded from Central America (Mexico and Panama) 

 and California, is especially injurious to the woodwork of buildings and other structures, 

 and such injury in the Southwestern States and in California may be due to this or 

 closely allied species of Calotermes. This species excavates chambers in the interior of 

 the solid wood, rather than honeycombing it as do species of Leucotermes. (PI. IV, fig. 

 1.) An indication of the infestation by Calotermes is the small oval sculptured pellets of 

 excrement expelled by the insects. There is a record of damage to painted dry siding of 

 a railroad business car at Los Angeles, Cal., by Calotermes, Apr. 6, 1915, and to the pine 

 sill of a porch at P,alin Beach, Pla., May 4, 1915, by Cryptotermes cavifrons Banks. 



2 In Baltimore, Md., and in Charlotte, N. C, the plaster laid on wood and patent metal 

 lathing was probably only incidentally bored to allow the colonizing sexed adults to 

 emerge at the time of the annual swarm. 



