380 SANITARY ENTOMOLOGY 



Periplaneta wwstralasiae (Fabricius) Burmeister 



This species is of the same general size and appearance as americana 

 and has practically the same habits. It is readily distinguishable from 

 that species by the elytra, which have an elongate yellowish spot bor- 

 dering the outer margin next the pronotum. The yellowish margins of 

 the pronotal disk is in greater contrast to the more clearly delineated 

 central portion than in americana and the general size is also somewhat 

 less. 



This roach is found mostly in warmer regions and is more often than 

 any other species reported as injurious to plants in greenhouses, conserva- 

 tories, etc. 



KEMEDIES 



Remedies galore, good, bad, and indifferent, mostly the latter, have 

 been recommended for use against roaches. No extended discussion of 

 the divers methods proposed for the discouragement or destruction of 

 these household pests will be here entered into. Only a few of the more 

 promising methods of eradication will be considered. 



Fwmigation 



Hydrocyanic Acid Gas 



In extreme infestation the best method of ridding a premise of 

 roaches is by fumigation, the best fumigant being hydrocyanic acid gas 

 at the rate of 10 ounces per 1,000 cubic feet for one hour. While thor- 

 oughly effective, this treatment involves considerable cost, and, owing to 

 its extremely dangerous qualities, necessitates extreme care in its appli- 

 cation. Before attempting fumigation with this POISONOUS gas, de- 

 tailed directions should be carefully studied. Such directions are given 

 in the lecture on the control of human lice (p. 324). 



Carbon Bisulphide 



A fumigant less dangerous to use than the above, but one requiring 

 much precaution because of its inflammability, is carbon bisulphide. This 

 highly volatile material distributed in open vessels, one pound to each 

 1,000 cubic feet of space, will destroy roaches, but the rooms fumigated 

 must be ones that can be very tightly sealed up, as iildeed must be the case 

 in any fumigation. This method is well adapted for use in the holds of ships 

 and other vessels. A fumigation of twenty-four hours will kill all vermin 

 in a tightly sealed room. The violently explosive nature of this material 

 necessitates extreme care in its use. No fire of any kind must be about 

 when it is in use. 



