170 DESTRUCTIVE INSECTS OF VICTORIA : 



present methods of dealing with scale insects and aphides on house 

 plants. 



JTi/drocyanic Acid Gas for Dwelling Fumigation. — 1 mention thesubject 

 principally to condemn this dangerous practice. It has been suggested, 

 not unnaturally, by the highly successful results obtained in destroying 

 orchard pests by the gas. Almost needless to state, the chief intent of 

 house fumigation is to effect the destruction of tiiat unmentionable, but 

 in. this colony by no means uncommon, insect, which is recognised in 

 scientific circles by the appellation Acanthia lecUdai'ia. The gas, when 

 used at double the strength for orchard treatment, does have a most 

 beneficent effect on the creatures, but it does not often accomplish a 

 complete riddance. The construction of most colonial houses is too 

 faulty for thorough work, currents of air entering crevices and diluting 

 the gas in them to a degree at which it is not deadly ; by virtue of this, 

 a few of the vermin or their eggs are tided through the deadly visita- 

 tion to their mates. Extermination being improbable, there is little 

 to induce one to give this remedy preference over less dangerous 

 measures, and I think that parties, other than experts, who know just 

 what risks are assumed, and what to do in case of an accident, are 

 wholly unwarranted in employing it. Even experienced hands had 

 best avoid its use under ordinary circumstances. Hydrocyanic acid gas 

 is not a poison to trifle with, and as a warning to those whose 

 enthusiasm over its iinrivalled insecticidal properties leads them to 

 meditate its use in their dwellings, I invite their consideration to the 

 fact that I have learned of several instances within the last year of 

 parties having narrowly escaped death when such use was being made 

 of it. The danger is not in the generation of the gas, but in the sub- 

 sequent opening of the rooms for ventilation, and iu the risk of parties 

 entering the rooms unawares during the operations or too early after 

 they are over. The danger attached to orchard fumigation or the use 

 of the gas in special chambers is infinitesimal in comparison. In con- 

 nexion with these uses of the gas, I have not heard of a single 

 accident occurring in this country, and only one, a temporary prostration 

 due to deliberate disobedience, in America. 



In Part I. of our Handbook several pages are taken up 

 with descriptions of the various kinds of fumigating 

 apparatus, as also ilkistrations of same, these having been 

 taken from American publications. As a ready means of 

 combating scale on trees, especially those of the citrus 

 family, large deciduous trees being much more difficult of 

 treatment by the gas tents, the cyanide treatment has 

 much to recommend it, the principal objection, according 

 to the best up-to-date American experts, being the matter 

 of cost. 



