176 THE CANADIAN ENTOMOLOGIST. 



from the second pair of tracheae do not serve the border at all, but con- 

 fine themselves to the region of the developing imaginal appendages. 



The withdrawal of the spiracles so far from direct contact with the 

 outer air produces a condition of isolation that should influence the 

 results of experiments with such material as hydrocyanic acid gas. Such 

 was found to be the case. While the insect is quite easily killed by rather 

 smaller charges than is considered necessary for efficient work with scale 

 insects, the time of exposure required is distinctly longer. It at least 

 suggests the possibility that considerable time is necessary for the 

 diffusion of the poison through the air of the breathing folds before reach- 

 ing the body. 



INSECTARY REARINGS OF TWO SPECIES OF 

 MORDELLISTENA. 



BY F. M. WEBSTER, WOOSTER, OHIO. 



Mordellistena pustulata, Mels., was reared June 6th, 1899, from stems 

 of Ambrosia trifida, Giant Ragweed, collected October 13th, 189S. From 

 the same species of plant collected November 10th, 1899, this insect was 

 reared April 4th, May 12th and 31st, 1900. 



Mr. Coquillett has found larvae of this species in plant stems, under 

 circumstances that render it highly probable that they were feeding on 

 Lepidopterous larva?. The stems of the Giant Ragweed are populated by 

 Lepidopterous, Dipterous, Coleopterous and Hymenopterous larvae. In 

 my case only by Coleopterous and Hymenopterous larvae. 



Mordellistena limbalis, Mels., was reared March 16th, 1901, from 

 thorns of the Honey Locust, collected February 20th, 1900. No other 

 insects had been reared from these thorns. 



Mr. Schwarz thinks that the larvae of Mordellistena Floridensis live in 

 the stems of plants, deriving their nutriment therefrom; while Mr. Osborn 

 found similar larvae probably feeding on Dipterous larva?, and also in 

 plant stems. 



Mr. A. W. Hanham has recently been removed from Winnipeg. 

 His address is now : Bank of British North America, Victoria, B. C 



