REPORT OF PROF. R. W JONES. [21] 



All the foregoing I u.sed frequently aud freely diluted witli varying quantities of 

 water. None of them injured the worms, either on cotton (Heliothis and Aletia) or 

 those on cabbage, ruta ba^as, &g. 



I made a decoction of China leaves and small twigs. This I sprayed freely on the 

 cotton plants, aud I think it had a Jarge effect in preventing the moths of Heliothis 

 and Aletia from ovipositing ; but it did not destroy the larva3. The alcoholic extract 

 of the China berries and leaves, adulterated with twice its quantity of water, was 

 sprayed on twelve Aletia larvae, full grown. Most of them fell to the ground, and four 

 died. This experiment was repeated several times, with about the same result ; but 

 when the extract vras diluted with ten parts of water it failed to bring the worms to 

 the ground. I concluded from this fact that the cost, of the alcohol would be so great 

 as to prevent the use of this preparation. 



I made a decoction of elder (Samhucus canadensis), using the leaves, small twigs, and 

 berries; also an infusion of the same. This, projected in spray on Aletia, Heliothis, 

 and on the worms infesting cabbage, caused them to cease eating, and in several in- 

 stances caused them to abandon the plant, whether cotton or cabbago. It is well 

 known that in all such cases the cotton worm is much more likely to be devoured by 

 predaceous insects than it is to reascend the plant. 



Pyrethrum. — As an insecticide this is superior, incomparably superior, to all other 

 substances with which I have experimented. I used it in powder diluted with wheat 

 flour, and as an extract variously diluted with water. The success attending my ex- 

 periments with this were eminently gratifying and satisfactory. 



It may be proper to remark that I used the pyrethrum (Buhach) raised by G. N. 

 Milco, of Stockton, Cal., some sent me from the headquarters of the U. S. Entomo- 

 logical Commission under the name of " Caucasian Insect Powder," and some which 

 I purchased of Messrs. Bullock & Crenshaw, Philadelphia, Pa,, as ''Persian Insect 

 Powder." 



When used in the state of dry powder, that of Milco seemed to have a considerable 

 advantage, but the others seemed to be quite equal to it in the power to yield deadly 

 extracts. 



Mode of preparing powder : 1 part of pyrethrum to 20 parts of wheat-flour, thor- 

 oughly mixed and shut up in a tight tin box for twenty- four hours. This blown by 

 bellows proved very efficient in destroying Aletia and cabbage worms which it touched. 

 It did not kill squash bugs, though it drove thema for the time from the plants. It 

 killed the Boll Worms upon which it was projected, but did not disturb those that 

 were concealed within the bolls. 



Extracts : A. Made with common (ethyl) alcohol 95 per cent. B. Made with methyl 

 alcohol (wood spirit). 



In all my first preparations I proceeded as follows : 



I introduced into a glass flask about 4 ounces of insect powder and added about 

 half a gallon of alcohol, corked and allowed to stand for twenty-four hours. I then 

 perforated the cork and introduced a glass tube, one fourth of an inch in diameter 

 and 36 inches long ; then subjected the flask to the well regulated heat of a water bath, 

 not allowing the temperature to reach the boiling point of alcohol. I usually applied 

 this gentle heat for about five hours, then set aside to cool. At first I decanted the 

 extract from the residue, and before using, diluted with water, as shown in the ex- 

 periments mentioned farther on. Subsequently, I shook up the solid residue of the 

 insect powder with the extract and diluted the whole witli water, aud in applying 

 kept the solid matter suspended by agitation. I found the latter plan economical. 

 The residue being wet with alcohol, readily spreads throughout the water and evi- 

 dently adds something to the value of the extract. 



I have never seen any statement or suggestion in regard to the use of wood spirit 

 as the menstruum. It occurred to me to try it. I found it to be a quicker solvent 

 of the essential oil and coloring matter of pyrethrum powder than common 95 per 

 cent, alcohol. I find that 1 pint and 2 ounces (by measure) of wood spirit will ex- 

 tract all the useful material out of an ounce of pyrethrum. Good wood spirits can 

 be bought for $1.25 per gallon. The extract made with wood spirit will bear dilu- 

 tion with a somewhat larger quantity of water than the extract made with ethyl al- 

 cohol. 



On this point I state my results thus : One pound pyrethrum powder to 20 pints (2^ 

 gallons) wood spirits. This can be safely diluted in the earlier part of the season 

 when the worms are small with forty parts of water. Hence one jjound pyrethrum 

 aud 2^ gallons methyl alcohol will when diluted make 100 gallons of liquid for the 

 destruction of insects. Allowing 40 gallons to the acre, the cost of this insecticide 

 would be $1.50. With improved atomizers this will be lessened. 



Wood spirit is more volatile than ethyl alcohol. This, I think, gives it considerable 

 advantage over ethyl alcohol as the solvent for the essential oil of the pyrethrum, 

 when the extract is to be used for Boll Worms that are working on the contents of 

 bolls. By its ready volatilization it distributes the insecticide rapidly into the adja- 

 cent air, and when not directly thrown into the hole cut by the Boll Worm it is car- 



