252 ENTOMOLOGY FOR MEDICAL OFFICERS 



termites are at first fed on saliva, afterwards on regurgitated 

 food or on excrement that is still nutritious. Many different 

 kinds of insects live as commensals in termite colonies. 



The ravages of termites in tropical countries are notorious, 

 everything in the form of wood or vegetable fibre is eaten, 

 and large beams of timber may be demolished unnoticed, 

 only a deceptive " shell " being left. The entire woodwork of 

 a house may be destroyed, and unprotected railway-sleepers 

 may be honeycombed as soon as they are laid. On the 

 other hand, in the general economy of tropical nature these 

 insects play a necessary part in bringing dead timber back 

 into the living stream of energy. 



In out-of-the-way places a medical officer is sure to be 

 consulted as to the protection of buildings, etc., from the 

 attacks of termites. Certain kinds of timber are distasteful 

 to termites : in India, sal and teak have this reputation : in 

 my old house in Calcutta there were beams of sal that must 

 have stood for nearly a century, and beams of teak that had 

 been in place for scores of years, and although there were 

 plenty of termites in the walls, and the ends of a few of the 

 beams had at different times been sampled by them, I hardly 

 remember any instance of a beam showing evidence of an 

 attack that had been at all sustained. Probably other kinds 

 of equally hard, dense, aromatic wood are equally resistant. 

 One of the cheapest and most effective deterrents is petroleum 

 residue (" blue oil "), applied without stint. For buried timber, 

 tarring, or impregnation with a strong solution of the cheaper 

 metallic salts {e.g. mercury and copper), or even superficial 

 charring, may be recommended. 



A fine account by Smeathman of one of the African 

 species of termites is to be found in the Philosophical Trans- 

 actions of the Royal Society for 1781, vol. Ixxi., pp. 60-85. 

 Smeathman states that from the periodical swarms of winged 

 males and females that leave the nest, future kings and 

 queens are captured by casual workers and "are elected 

 kings and queens of new states." 



Order Embiida. 



This order includes one small family of small insects — the Embiida — 

 which somewhat resemble a slender termite and are sometimes included 



