195 



These tables (two out of niauy) arc followed with the re- 

 mark : 



" Eefereiice to the two tahles shows that the })ereentage of uu- 

 " treated " Aphis " gradually increased from the first day of the 

 " tests onward. The increase was due to the birth of new 

 '^ Aphids on the untreated plants. Aphids were also born on the 

 "treated plants from the time the insecticide was applied, until 

 " the reproducing mothers had died. tSiiice, practically, all the 

 " Aphids on the treated plants were dead at the close of the tests, 

 "the newly born young ones must have been killed by coming in 

 "close proximity to the particles of powder still remaining: on tlic 

 " plants.'' 



Efficiency of '" Tuba " as a Stomach Poison against 

 Yakious Insects. 



Polalo Beetle larvae. Tuba used in various strengths u|) to 1 

 pound of jx^wder to 128 galls, of water was found very effective. 

 Practically all larvae were killed within 48 hours. Applied as dust 

 the tests were equally couclusive. 



'rent Caterpillars. All mixtures viarying in strength fi-om one 

 pound to S gallons of water to 1 pound to 200 gallons weri' found 

 effective. 



Apple— tree branches were thoroughly sprayed und, aft(u- the 

 foliage ha<l dried, 20 to 40 newly hatched larvae were ])la('ed on 

 each branch. The caterpillars hcgaji to show signs of discomfort 

 within 48 hours and were practically all dead in from ."> to 10 days. 

 In no case, Avas any material amount of feeding obser\ed. In a 

 second series of tests the larvae were placed on the branches and 



