196 



sprayed after they had begun to form their tents. Ciider thesd 

 conditioiis. sprays containing one pound ot powder to 50 gallons of 

 water and 1 pound to lOO gallons, killed all the larvae within 24 

 liours. Wlien 1 pound to 200 gallons and 1 pound to 400 gallons of 

 water were used, all the larvae were not killed within 11 days. I)ut 

 the lew whieh remained alive were very small and inactive. 



I'sed as a dust, this material killed all the treated larvae 

 within a week. 



Oak-W'onits. Two small oak trees, on which about ;!<•(» cater- 

 pillars (Ani.sola- Seiiatoria) were feeding, were sprayed thoroughly 

 with Tuba at the rate of 1 jwund of powder to 25 gallons of water: 

 soap was added at the rate of one pound to 50 gallons, and a 

 kiiapsack-s])rayer was used. Within 24 hours, the larvae became 

 inactive and ceased to feed, and at the end of 6 days no living ones 

 luuld he found. As a check on this test, powdered arsenate of 

 lead was ajjplied at the rate of 1 jK)und to 50 gallons of water, and 

 almost identical results were obtained. 



Jl i/j)li('iilrl(i < 'lined (caterpillars wjiich weave a we!) inside 

 which tliey work, devouring the foliage t'liclosed). The cater- 

 pillars ahoiit one third grown, were killed within a week by a 

 s])ray of 1 pound of powder to 5 gallons of water. Mixtures rang- 

 ing from ] jjound to 5(i gallons to 1 })ound to 200 gallons of water 

 were not satisfactorily effective, since nearly all of the sprayed 

 foliage was eaten and not all of the caterpillars were killed. 



Dalana hirvac. Two apple-trees, on which large colonics of 

 nearly full-grown a])ple datanas (Daiana ininislra) were feeding, 

 were sprayed with Tul)a at the late of 1 pound to 50 gallons of 

 water. 'J'wenty-four hours later, one living larva was found on 

 one tree, and two on the other tree. The ground under the trees 

 was thickly sprinkled with dead larvae. 



Cahhiu/r Worms. Applied at the rate of I pound to 25 gal- 

 lons of water all the larvae in two cage-tests were killed within 24 

 hours. 



Methods were cmployc(| to trace the tul)a-])owder and spray 

 mixtui'cs in the hodies of insects and the results show that tul)a 

 powder dusted upon insects does not ])ass into the trachae, hut a 

 iiiuiteil amount of it may lodge in the spiracles: in order that the 

 vapouis and exhalations from a spray be ett'ective. it is necessary 

 for the sprayed insects to carry some of the solution on. their bodies, 

 in order that the exhalation may pass into the spiracles in as un- 

 diluted a comlition as possible. After being dusted the insects 

 seem U) swallow some of the power which later may act as a .stomach 

 pois.)n. Soap solutions containing tu1)a extract i)ass freely into the 

 spiracles ami (inally reach the various tissues, but probably the 

 extract kills hy lii'st alfecting the ner\-e-tissue. (The above; ])hysio- 

 loL;i(al (onclusions are hased on nn'croscopical examiiuit iiuis and 

 chemical manij)ulatioiis too long and too technical to he inserte(l 

 in tlii> papi'r). 



