178 REPORT 4, UNITED STATES ENTOMOLOGICAL COMMISSION. 



was applied freely, the upper surface of the leaves so far as they were not protected 

 by others above them being pretty thoroughly wetted. Results far from being sat- 

 isfactory. A large number of worms were affected and killed, but a far greater 

 proportion did not come in contact with the fluid, and were consequently not affected. 



JExperiment 2. — The liquid was again applied by means of the fountain pump, but 

 from one side. In this case the jets strike the leaves and branches with considerable 

 force, and the liquid is consequently much more scattered than in the applicatiou 

 from above. The result was that by far the largest portion of the worms were affected 

 and killed, but there remained enough on the plants to do serious injury. 



Experiment 3. — The liquid applied as in the foregoing experiment, but from the two 

 opposite sides. Two comers of the field were treated in this way. Result : The plants 

 were effectually freed from the worms, and only a very few full-grown ones were 

 found about twelve hours afterwards. I must state, however, that the amount of 

 liquid used in this mixture was very large, estimated at the rate of not less than 80 

 gallons per acre. 



Experiment 4. — The liquid applied by means of the parlor atomizer. This could nat- 

 urally be carried on only on a very small scale, but was often repeated. The result 



1 can draw from this experiment is that the very fine, mist-like spray of the atomizer 

 is most effective, and even more so than a coarse and copious spray. 



One pound of Pyretlirum, if used at the rate mentioned in these ex- 

 periments, viz., 200 grains of the powder to 2 gallons of water, could 

 thus be diluted with 75 gallons of water, which would be sufficient for 



2 J acres of cotton, calculating 30 gallons per acre. The cost of this ap- 

 plication (not counting in labor and machinery), consists only in that of 

 the powder, and putting this down at 75 cents per pound, we arrive at 

 the amount of 30 cents per acre of cotton. It must further be considered 

 that 30 gallons of liquid per acre, applied with the improved atomizers, 

 is a liberal allowance, and that, therefore, the cost of the application 

 can in all probability still be lowered considerably without loss in 

 efficacy. At any rate, this method of applying Pyrethrum is by far 

 cheaper and simpler than any other at present known to us. It is of 

 course not free from the principal drawback of Pyrethrum as an insec- 

 ticide, and a repeated application is necessary to protect the cotton 

 from one generation of worms. But even this double application is 

 cheaper than the dry Paris-green remedy, as carried on by the sifting 

 method. 



5. The tea or decoction of Pyrethrum.— Professor Hilgard, 

 who first called our attention to this method of using Pyrethrum, ex- 

 presses himself most favorably as to the results of this experiment. 

 He says : 



I think, from my experiments, that the tea or infusion prepared from the flowers 

 ( which need not be ground up for the purpose) is the most convenient and efficacious 

 form of using this insecticide in the open air ; provided that it is used at times ivhen 

 the water will not evaporate too rapidly, and that it is applied, not by pouring over in a 

 stream, or even in drops, but in the form of a spray from a syringe with^/ie holes in its 

 rose. In this case the fluid will reach the insect despite of its water-shedding sur- 

 faces, hairs, &c , and stay long enough to kill. Thus applied, I have found it to be 

 efficient even against the armored scale-bug of the orange and lemon, which falls off 

 in the course of two or three days after the application, while the young brood is 

 almost instantly destroyed. As the flower tea, unlike whale soap and other washes, 

 leaves the leaves perfectly clean and does not injure even the most tender growth, it 



