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NOTE ON THE IMMUNITY OF CHALCTD PARASITES 

 TO HYDROCYANIC ACID GAS. 



By E. ERNEST GREEN. 



Wishing to kill a few individuals of a species of Lecanium, for pre- 

 servation as cabinet specimens, I subjected them to the fumes of strong 

 hydrocyanic acid gas (in an ordinary cyanide bottle) for a period of 

 eighteen hours. In spite of this drastic treatment, large numbers of 

 living Chalcids emerged from the bodies of the Coccids after their 

 removal from the killing-bottle. 



This immunity of internal parasites may have a bearing upon the 

 treatment of 'Scale Insects' in the field, when they are known to be 

 infested by useful parasites. It would now appear to be possible to 

 fumigate scale-infested trees, with a fair probability that any Chalcid 

 parasites that may be developing within the bodies of the Coccids will 

 escape — to carry on their useful work elsewhere. 



