PYRETHRUM AS USED AGAINST THE COTTOX WORM. 171 
upon very young Cotton Worms, the powder experimented with being 
the Californian buhaeh : 
All the larvie experimented with were hatched last night (August 10) from eggs 
laid in breeding jar during the night of August 7, except larva (n) 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 ; larvae affected in 15 seconds; convulsed in 1 minute and 
IS seconds; died in p. m. 
(b) One minute fragment applied on back (anterior segments) ; fragment dropped 
oft' 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 mieroscopie fragment applied with needle-point to side near spira- 
eles; evidently affected in fifteen seconds; convulsed in 1| minutes. Fragment ad- 
hered 1 minute. Larva died in p. m. 
(</) One \ery minute fragment (almost microscopic fragment) applied on side of 
body near middle, Larva lost sight of during 4 minutes, at end of which time WM 
entirely convuLed. Died iu p. ni. 
(e) Several (three or four) small fragments applied on side of body; affected in 
30 HQondlj convulsed after 9 minutes, 16 seconds. Died in p. m. 
(/) One minute fragment on middle of back ; affected in 1 minute, 15 seconds : con- 
vulsed in 3 minutes; fragment dropped off in 3 minutes. Four o'clock p. in., larva 
recovering; later, went to eating; entirely restored. (August l'J, alive andwt 11.) 
((/) One microscopic fragment on back at anal extremity of body and very soon lost 
oft' ("JO seconds .'). Seemed aft'eeted aJ'ter 5 minutes; examined after "J hours; seems not 
injured. In ]>. in. entirely well — see (g) below. 
(h) One large fragment (size of w blow - 1 1 \ " egg) applied for 5 or 6 secomls to side 
of body, near or upon spiracles; aft'eeted in 2 minutes; convulsed in 4 minutes j 8 hour>. 
unable to move about; 4.30 p. m., still alive but disabled. Died before night. 
(i) One entirely microscopic fragment applied to back of neck; aft'eeted in H min- 
utes; convulsed in 3 minutes; 4.30 p. m., appears recovering. (August Li, larva died 
this morning.) 
(k) One entirely microscopic fragment applied underneath anterior segments be- 
tween lee-,; adhered only a few seconds: appears affected after lf> minutes, but, able 
to move about; 4.30 p. m., recovering and eating; later, fully recovered., (August 12, 
alive aud well.) 
Noti:.— Larva' (/) (m) and (h) were treated as follows: A small quantity of pyrethrum 
placed on a piece of paper was lightly sprayed with an atomizer, and allowed tore- 
main covered with drops of moisture for about ten minutes. The larva* were then 
touched with a needle dipped in this poisoned dew. 
(0 A single, veiy slight, and probably insufficient application beneath anterior seg- 
ments; no nioi^t uri' adhered to larva; affected after 1 minute, 16 seconds; 1 hour later 
appears torpid, but not convulsed; 4 p. m., recovered and eating. (August 12, alive 
and well.) 
(m) Touched with poisoned dew about anterior segments aud moisture left upon back 
of the segment, more thoroughly applied than in preceding larva; aft'eeted in 45 sec- 
onds; couvulsed in 2 minutes; 4.30 p. m., recovered. (August 12, alive and well.) 
(w) 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. 
(g) Second experiment with larva (g) made in p. m. One fragment (size of " blow- 
fly " ^££) 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. 
