[14J 



REPORT 4, UNITED STATES ENTOMOLOGICAL COMMISSION. 



I believe also that a broad glare, like that of a bonfire, attracts a greater number 

 than the concentrated light of a lantern. I have also known them to fly at the glow- , 

 ing end of a cigar. 



That the moths are exceedingly fond of fruit, is a fact too well known to require 

 iteration. I found them clustering upon figs, peaches, and especially upon persimmons, 



which attract them from great distances. 



# * * » * * * 



EXPERIMENTS WITH POISONS. 



Pyrethrum. — Samples of the powder sent me by the Commission were of two sorts, 

 Milco's Californian Buhach and an imported product. To test their relative strength, 

 sixty Cotton Worms were collected and divided into two lots, as equally as possible, so 

 that neither set should contain an undue proportion of old or of young worms. Each 

 set was placed in a Mason jar, and thoroughly dusted with a small quantity of 

 powder, one jar with the Buhach, the other with the imported pyrethrum. The 

 worms were immediately afterwards turned out upon newspapers spread upon the 

 ground. Those dusted with Buhach were paralyzed and unable to crawl about in 

 from 15 to 20 minutes. Those treated with imported pyrethrum were similarly 

 aftected in from 25 to 30 minutes. In both lots the worms began to be affected in less 

 than one minute, and nearly all died within 12 hours. Another experiment was made 

 upon one hundred worms of all sizes, in which the powder (imported) was applied in 

 the open ^ir by means of a bellows. Worms one-fifth to one-third grown were com- 

 pletely paralyzed in 10 minutes; worms one-half grown in 30 to 45 minutes; full- 

 grown worms showed the full effect of the poison after several hours. In about three 

 hours the smaller worms appeared to be dead. The oldest worms did not die before 

 night. Experiments were made in the field upon Aletia larvae, using very small 

 quantities of pyrethrum powder. A few particles dropped with the fingers upon 

 worms from half to full grown produced convulsions in from 3 to 10 minutes. The 

 action of the poison is much more powerful upon young than upon old worms, but 

 depends in each case less upon the amount of powder used than upon the part of the 

 body it first touches or the method of applying it. Very small particles placed upon 

 the sides of the larvae, especially near the anterior spiracles, produce a more marked 

 effect than larger quantities dropped upon their backs or lodged among the hairs. 

 The effect is also enhanced by driving the powder with force against them, by means 

 of a bellows, for example, as the particles are thus driven into closer contact. The 

 effect of Californian Buhach (pyrethrum) powder upon young Aletia larvae is shown 

 in the following experiments, the object being to ascertain the minimum quantity 

 that could be used with effect : 



All the larvae were hatched last night (August 10), from eggs laid in breeding jar dur- 

 ing the night of August 7 (except larva [?i], which was only a few hours from the 

 «gg)- 



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

 body) with the point of a needle : larva affected in 15 seconds ; convulsed in 1 

 minute and 15 seconds. Died in p. m. 

 (&) One miuute 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 re- 

 covered. P. m., went to eating and fully recovered. This is a very vigorous 

 larva, probably severalhours older than the rest. (August 12th ; has grown 

 larger, and eating well.) 

 (c) One almost microscopic fragment applied, with needle point, to side near 

 spiracles: evidently affected in 15 seconds; convulsed in 1^ minutes. Frag- 

 ment adhered one 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 (3 or 4) small fragments applied on side of body : affected in 30 seconds ; 



convulsed after 2 minutes 15 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. m., 

 larva recovering; later, went to eating; entirely restored. (Aug. 12, alive and 

 well.:) 

 {g) One microscopic fragment on back at anal extremity of body and very soon 

 lost off (20 seconds ?). Seemed affected after 5 minutes ; examined after 2 

 hours, seems not injured. In p. m., entirely well [see (</')]• 

 {Ji) One large fragment (size of" blowfly" egg) applied for 5 or 6 seconds to side of 

 body, near or upon spiracles: affectedln 2 minutes; convulsed in 4 minutes; 

 2 hours, unable to move about; 4.30 p. m., still alive but disabled. Died be 

 fore night. 



