NEUROPTERA. 415 



formed of agglutinated material, which are stuck along the walls in 

 the cellars and the apartments, or else suspended to the roof like 

 stalactites. Certain parts of Agen and of Bordeaux begin also to 

 suffer from the ravages of these insects. The danger appears to be 

 imminent. 



We are indebted to M. de Quatrefages for some interesting experi- 

 ments on the termites of La Rochelle. Not only has the learned 

 naturalist helped to make known to us the habits of these dark-loving 

 insects, but he has also told us how to destroy them. Different 

 substances have been tried in vain to stop these terrible ravages 

 essence of turpentine, arsenical soap, boiling lye, &c. M. de 

 Quatrefages had recourse to gaseous injections. He tried succes- 

 sively binoxide of nitrogen, nitric acid, chlorine and sulphurous acid ; 

 chlorine, above all, fully answered his hopes. With pure chlorine he 

 killed the termites instantaneously ; mixed with nine-tenths of air, he 

 suffocated them in half an hour. " For attacking the termites," says 

 M. de Quatrefages, " one ought to choose by preference the period of 

 their reproduction, so as to destroy the pregnant females. It is 

 probable that, like their exotic congeners, the termites of France will 

 endeavour to defend themselves by walling up the interior of their 

 galleries at the first signs of an attack. The operator must then act 

 with a great deal of promptitude, and direct the apparatus as much as 

 possible into the very centre of their habitation, where the galleries 

 are the broadest and the most numerous. 



" With whatever care one acts, and whatever may be the success 

 of a first attempt, it seems to me impossible to destroy in one cam- 

 paign all the termites of a locality. In this, as in all operations of the 

 same kind, a certain amount of perseverance is necessary, especially 

 if it is in a town or in a country infested by them to a very great 

 degree; in that case one will be forced to repeat the operation from 

 time to time. When, on the contrary, the termites are already 

 cantoned, it seems to me that the success ought to be lasting. This 

 is fortunately the case at La Rochelle ; and by knowing how to profit 

 by it, one may doubtlessly prevent the spread of these pests, which at 

 one time or another, may attack the whole town."* 



In 1864 the Lords of the English Admiralty addressed an inquiry 

 to the Entomological Society of London, on the best means of pre- 

 serving wood from the attacks of the Indian termites. In answer to 

 this inquiry, the Entomological Society recommended many processes : 



* ' ' Memoires sur la destruction des Termites. " Annales des Sciences Naturelles, 

 3e serie, tome xx., p. 15. 



