194 



THE AMERICAN ENTOMOLOGIST. 



able to run, and it moves its legs in a 

 drunken sort of way. 



July 2ist. — One of the beetles, which 

 yielded to the powder two days ago, lies 

 helpless on its back, but keeps up a con- 

 stant twitching of the last joints of the 

 legs, showing life, but nothing more. It is 

 now more than fifty hours since it ceased 

 to walk, and yet it is alive. 



The powder dusted over the vine has 

 completely freed the vine from its ene- 

 mies. 



August 2d. — One week ago rain fell. ■ A 

 few beetles are now found about the vine. 



On Cabbage Worms. — July igth. — 

 The imported Cabbage Butterfly {Pieris 

 rupee') is now to be found everywhere in the 

 vicinity of cabbage patches. As they were 

 found about thistle-blossoms, an effort was 

 made to dust powder upon them, as they 

 rested, gathering the honey. This is easily 

 done, but the creature is found to fly away 

 and continue its search for food for some 

 time. Of several so dusted only one is 

 known to have yielded to the powder. 



Four were caught and dusted with the 

 powder, and allowed to fly about in the 

 room, where they could free themselves, 

 if possible, from the effects. In three 

 minutes they showed signs of irritation, 

 and in two more their movements were 

 drunken, the power of flight rapidly yield- 

 ing to the poison, which seems always to 

 affect the limbs first. In ten minutes they 

 were helpless, and after five hours not yet 

 dead. 



At the same time the worms of this 

 species were dusted, and in two minutes 

 showed signs of pain, and grew rapidly 

 helpless. A very little of the powder evi- 

 dently would suffice for these. 



In one instance about thirty of the 

 larvae, mostly full grown, were placed in a 

 tin box, in which was dropped one of the 

 Blister-beetles, that had adhering to its 

 body such of the powder as remained 

 after the beetle had struggled to clean 

 itself. In an hour and a half from the 

 time the box was closed (after placing 

 within it the beetle) it was opened, and 

 all but seven of the worms found dead, or 



dying, and they had avoided contact with 

 the beetle by crawling to the top of the 

 box. 



The power of even a minute quantity 

 of the powder is thus shown to be effect- 

 ive with these pests. 



On Squash Bugs. — July 2jd. — A 

 pumpkin vine was found, upon which 

 were a few full-grown Scjuash-bugs, and 

 hundreds of smaller ones — enough to en- 

 tirely kill the vine in a short time. Upon 

 a])plying the powder, the bugs did not 

 seem to show much irritation, and it was 

 even surmised that they would not yield 

 to its effects. ' Four hours later, however, 

 it was found that, with hardly a single ex- 

 ception, they were dead, or dying, and lay 

 in great number on the ground, directly 

 under the very leaves upon which they 

 had been feeding. 



On Roaches. — July 24th. — One of the 

 clerks at the Treasury Department com- 

 plained of the Cockroaches infesting the 

 desks at which they work. Powder was 

 suggested, and tried upon one desk, and 

 for a week not one has been found about 

 the desk in question, though abundant 

 about the adjoining ones. 



EFFECT OF THE FUMES OF BURNING 

 PYRETHRUM. 



The Pyrethrum was burned by placing 

 it in a tin dish and applying a match. It 

 took fire easily, and biirned like sawdust, 

 giving off considerable smoke. 



The smoke was collected in a tight tin 

 case with glass sides. 



The first insects placed within were 

 locusts and crickets. These held to the 

 sides of the tin case for some four to five 

 minutes in the dense fumes before they 

 yielded and fell down. They acted much 

 as other insects do when under the influ- 

 ence of Pyrethrum (unburned). 



Carnivorous beetles seemed to hold out 

 even longer than the locusts. 



Flies in a wire gauze fly-trap were sub- 

 jected to the smoke, by blowing it through 

 the trap and burning it inside. They were 

 greatly irritated, as shown by buzzing 

 about, and by constantly rubbing the body 



