INSECT POWDEft. 

 Table 2. — Physiological examination of insect powder.^ 



23 



I'roduct. 



Time required. 



Mini- 

 mum. 



Maxi- 

 mum. 



Average. 



Commercial powder ground from wild flowers 



Commercial powder ground from Montenegrin closed flowers 



Commercial powder ground from Dalmatian half-closed flowers. 



Commercial powder ground from Dalmatian open flowers 



Commercial powder 



Commercial powder ground from open Dalmatian flowers 



Commercial powder ground from closed Dalmatian flowers 



Commercial powder ground from closed Montenegrin flowers. . . 



Commercial powder 



Powdered closed flowers grown at Korneuburg, 1913 



Powdered half-open flowers grown at Korneuburg, 1913 



Powdered closed flowers grown at Korneuburg, 1914 



Powdered half-open flowers grown at Korneuburg, 1914 



Powdered open flowers grown at Korneuburg, 1914 



Powdered stems grown at Korneuburg, 1914 



Min. Sec. 

 40 



Min. Sec. 



Min. Sec. 



09 

 43 

 34 

 00 

 05 

 28 

 18 

 04 

 02 

 53 

 18 

 lO 

 15 

 02 

 16 



' 50 tests were made on each sample. 



In testing the action of insect powder against various insects Smith 

 (263) and many other entomologists used different brands of com- 

 mercial insect powders. Their results were comparative, as they 

 were without samples of known purity, and their experiments are 

 without value in showing the presence of adulterants. 



MICROSCOPICAL METHODS. 



There has been much divergence of opinion as to the value of a 

 microscopical examination of an insect powder in determining its 

 genuineness. For instance, Jelliffe (148) concludes that ''the 

 microscope is the only possible means for detecting the presence of 

 powdered stems in insect powder." On the other hand, Beringer 

 (29), after examining genuine insect powder and the powder made 

 from the flowers of the Hungarian daisy, says, "Microscopically no 

 difference could be detected between the two powders." Howie 

 (139) states that he finds chemical methods more exact and trust- 

 worthy than microscopical ones for detecting added fustic, chrome, 

 and turmeric. Again, in discussing Kirkby's (156) paper, he says 

 that he has little faith m microscopical observation for ascertaining 

 the value of an insect powder, the physiological test with the black 

 beetle being the best. 



For recognizing the presence of certain adulterants, as for instance 

 starch or starch-bearing materials, the microscopical examination 

 is of great value, but in the powdered state flowers of certain of the 

 Compositse closely allied to Pyrethrum are so similar to insect flowers 

 as to render their detection difficult. Again, although an adulterant 

 can usually be detected qualitatively by the microscope, no exact 

 quantitative method has as yet been devised for its determination. 



