278 Phylum Ar thro poda 



themselves; their growth rate is rapid; and they are far enough from 

 the adult stage to allow time for experiments of several months' dura- 

 tion. Individuals of different instars may be distinguished by their 

 relative head widths and the number of antennal segments (Heath, 

 1927). 



DRY-WOOD TERMITES 



The dry-wood termites which belong to the subgenus Kalotermes are 

 found in Mexico and in the southern part of the United States. They 

 live typically in the dry, sound wood of buildings and other wooden 

 structures. 



In choosing sound wood for feeding laboratory colonies of these 

 termites the pieces are looked over carefully and all pieces which show 

 evidence of a high content of resin or volatile oils are rejected. 



Examination of the wood upon which Kalotermes minor feeds in 

 nature has shown it to contain fungus mycelium, even when it shows no 

 macroscopic evidence of decay (Hendee, 1933). Therefore, if wood 

 other than that in which the termites have previously been living is 

 supplied to laboratory colonies, it is first infected with fungi so that it 

 will be similar to the natural diet of the termites. This is done by 

 dampening the wood, scattering crushed termite pellets over it, and 

 allowing five or six days to elapse before it is fed to the termites. By 

 that time fungus spores which were contained in the pellets will have 

 given rise to a growth of fungus mycelium in the wood. 



While Kalotermes does not require as much moisture as Zootermopsis, 

 the wood upon which it is fed should not be allowed to dry out com- 

 pletely. Light ( 1934) reports that many species of Kalotermes require a 

 minimum of 10% moisture in their food. 



Dry-wood termites will survive at ordinary room temperatures. For 

 normal growth and reproduction, however, they require a minimum of 

 25 C. For swarming, Harvey (1934) reports a temperature ranging 

 from 8o° to ioo° F. (27 to 38 C.) to be the optimum for Kalotermes 

 minor. 



Kalotermes minor is recommended by Kofoid and Bowe (1934) as 

 the best species for use in testing wood and other materials for termite 

 resistivity. They give a detailed account of the method of making the 

 tests. 



SUBTERRANEAN TERMITES 



Subterranean termites of the genus Reticulitermes are found in nearly 

 all parts of the United States. They demand a constant supply of 

 moisture and are found in wood so situated that they may maintain 

 runways into the soil. 



