REPORT OF H. G. HUBBARD. [15] 



(i) One entirely microscopic fragment applied to back of neck : affected in 1^ min- 

 utes ; convulsed in 3 minutes ; 4.30 p. m., appears recovering. (August 12, 

 larva died this morning). 

 (k) One entirely microscopic fragment applied underneath anterior segments be- 

 tween legs: adhered only a few seconds; appears affected after 15 minutes, 

 but able to move about. 4.30 p. ra.^ recovering and eating; later, fully recov- 

 ered. (August 12, alive and well.) 

 Xote. — Larvte (/) (w) and(70 "^'ere treated as follows : A small quantity of pyre- 

 thrum placed ou a piece of paper was lightly sprayed, with an atomizer, and 

 allowed.to remain covered with drops of moisture for about 10 minutes. The 

 larvae were then touched with a needle dipped in this poisoned dew. 

 (/) A single, very slight, and probably insufficient application beneath anterior seg- 

 ments : no moisture adhered to larva : affected after 1 minute 15 seconds ; 1 

 hour later, appears torpid but not convulsed. 4 p. m., recovered and eating. 

 (August 12, alive and well.) 

 (w) Touched with i')oisoued dew about anterior segments, and moisture left upon 

 the back of the segments; more thoroughly applied than in preceding larva ; 

 affected in 45 seconds ; convulsed in 2 minutes. 4.30 p.m., recovered. (Au- 

 gust 12, alive and well.) 

 {■)}) A very young larva, probably hatched late this morning, was allowed to crawl 

 along needle and over a drop of poisoned dew : instantly affected; convulsed 

 in 15 seconds. Died in p. m. 

 (//') Second experiment with larva (g) made in p. m. One fragment, size of blowfly 

 egg, laid on back, middle of body, not touching the skin, but adhering to hairs; 

 dropped off in 30 seconds; evidently affected in 45 seconds ; completely con- 

 vulsed in 2 minutes. Died in a few hours. 

 Pyrethrum powder was blown with a bellows upon AleMa moths clustering upon 

 ripe figs at night. The moths were evidently affected, but flew away in a few minutes. 

 No fresh moths alighted upon fruit thus dusted, but as the powder rapidly loses its 

 strength when exposed to the air, the protection afforded by it to fruit probably lasts 

 only a few hours, audit cannot therefore be recommended for this purpose. 



Tried upon different insects, it appears to affect the higher Hymenoptera more than 

 other insects. Ants are almost instantly affected. Wasps continue feeding for about 

 twenty seconds, and are violently affected in from one to two minutes. Larvae of all 

 kinds are more quickly affected than imagos. Termites, owing probably to their 

 tender bodies, are instantly affected and soon killed. Spiders resist longer than 

 anything else. They sometimes change their skins when dusted with the powder. 

 Copris and Phanceus are slightly affected, and long resist the action of the povrder. 

 ScoIopendridcB affected similarly to spiders. Bugs slightly affected, especially the 

 large and heavily armed predaceous species. Large grasshoppers slightly affected. 

 Roaches very violently affected. These observations refer to the immediate action 

 of the dry and undiluted powder, and are comparative only. There is no doubt thart 

 insects often recover from slight applications. 



Experiments in the field, with the dry powder sifted upon the plants, gave very uu- 

 satisfiictory results, unless large quantities of the powder were nsed. On August 28, 

 a very windy day, I tried an application with the bellows, allowing the wind to carry 

 the powder in fine clouds through the foliage, and using about one pound to the acre, 

 lu this way, owing partly to the impossibility of securing an equal distribution, 

 some worms were affected at a distance of ten or fifteen feet, while others, much nearer, 

 were not affected at all. I have reason to believe that very few worms were killed 

 outright at this trial. Some recovered in a few hours. A*^ number of those which 

 showed signs of pain, but had been very lightly dusted, I confined in vivaria, and all 

 completed their transformation in the usual time. At the time the foregoing experi- 

 ment was made, the leaves were quite wet with recent rain, and another heavy shower 

 occurred later in the day. 



Infusions made by pouring hot (not boiling) water upon the powder were found in- 

 effective and quite worthless. 



With a strong extract I have had blo opportunity of experimenting. Alcohol poured 

 upon the powder, extracts a sufficient quantity of the poisonous oil to be very effective 

 when used with an atomizer, but is too expensive for use on a large scale. ' 



London purple. — Several experiments were tried in which small quantities of this 

 powder were dusted upon the plants without diluents. Whenever a quantity was 

 used suflScient to kill the worms the leaves were badly scorched. 



Poisoning the moths. — At a time when the moths swarmed at night about the fallen 

 fruit under persimmon trees in the fields, I poisoned the fruit with London purple, and 

 also with white arsenic. In this way many moths were undoubtedly killed, but as 

 numbers of them flew away to die, the exact proportion could not be ascertained. 

 Under nettings covering cotton plants, moths were readily killed by giving them poi- 

 soned fruit. They do not appear to dislike the frjiit even when mixed with an excess 

 of London purple or arsenic, and settle quite as readily upon the poisoned as upon 



