PYRETHRUM AS USED AGAINST THE COTTON WORM. 171 



upon very young Cotton Worms, the powder experimented with being 

 the Calif ornian buhach : 



All the larvae experimented with were hatched last night (August 10) from eggs 

 laid inbreeding jar during the night of August 7, except larva (w) which was only 

 a few hours from the egg. 



(a) Three minute fragments of pyrethrum laid upon back (terminal half of body) 

 with the point of a needle ; larvsB affected in 15 seconds ; convulsed in 1 minute and 

 15 seconds 5 died in p. m. 



(&) One minute fragment applied on back (anterior segments) ; fragment dropped 

 off in 3 minutes ; probably only adhered to hairs of body 3^ minutes ; larva appeared 

 affected but slightly ; after three hours larva appears to have recovered; p. m., went 

 to eating and fully recovered. This is a very vigorous larva, probably several hours 

 older than the rest. (August 12, has grown larger and is eating well.) 



(c) One almost microscopic fragment a^^plied with needle-point to side near spira- 

 cles; evidently affected in fifteen seconds; convulsed in 1^ minutes. Fragment ad- 

 hered 1 minute. Larva died in p. m. 



(d) One very minute fragment (almost microscopic fragment) applied on side of 

 body near middle. Larva lost sight of during 4 minutes, at end of which time was 

 entirely convulsed. Died in p. m. 



(e) Several (three or four) small fragments applied on side of body ; affected in 

 30 seconds; convulsed after 2 minutes, 15 second^. Died in p. m. 



(/) One minute fragment on middle of back ; affected inl minute, 15 seconds; con- 

 vulsed in 3 minutes; fragment dropped off" in 3 minutes. Four o'clock p. m., larva 

 recovering; later, went to eating; entirely restored. (August 12, alive andwell.) 

 % (<7) One microscopic fragment on back at anal extremity of body and very soon lost 

 oft" (20 seconds ?). Seemed affected after 5 minutes ; examined after 2 hours ; seems not 

 injured. In p. m. entirely well — see (g) below. 



(h) One large fragment (size of "blow-fly" egg) applied for 5 or 6 seconds to side 

 of body, near or upon spiracles ; affected in 2 minutes ; convulsed in 4 minutes ; 2 hours, 

 unable to move about; 4.30 p. m., still alive but disabled. Died before night. 



(t) 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.) 



(fc) 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. m., recovering and eating; later, fully recovered. (August 12, 

 alive and well.) 



Note. — Larvce (I) (m) and (?i) were treated as follows : A small quantity of pyrethrum 

 placed on a piece of paper was lightly sprayed with an atomizer, and allowed to re- 

 main covered with drops of moisture for about ten minutes. The larvae were then 

 touched with a needle dipped in this poisoned dew. 



(/) A single, very slight, and probably insufiicient 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 

 andwell.) 



(m) Touched wdth poisoned dew about anterior segments and moisture left upon back 

 of the segment, more thoroughly applied than in preceding larva; affected in 45 sec- 

 onds; convulsed in 2 minutes ; 4.30 p. m,, recovered. (August 12, alive and well.) 



(n) 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 " blow- 

 fly " 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 convulsed in 

 2 minutes. Died in few hours. 



