482 STATE BOARD OF AGRICULTUllE. 



It was clear that the body secretions had dissolved some of the hellebore, 

 and had moistened more of it so that it stnck as a white crust on the 

 body. The indications were that but very little of the hellebore, dis- 

 solved in the body secretions, had been absorbed through the cuticular 

 covering — only enough to render the outer surface of the body numb and 

 clumsy. In the final stages, the insect seemed to be dying, more from 

 drying and from starvation than anything else — yet it was the hellebore 

 which first rendered the animal in an unfit condition for normal life- 

 processes. _ 



Borax powder and finely powdered sodium fluoride have been used as 

 etfective agents against cockroaches. It was known to be not at all 

 necessary to place these powders on a bait that should be eaten by the 

 roaches; the dry powders became effective if they were dusted in loca- 

 tions where the insects were sure to run. There seemed to be nothing 

 appetizing about the powders, in themselves, and it was a question Jiow 

 they became effective against roaches. The large American cockroach 

 [Periplaneta Americana) and the smaller croton bug were available for 

 study in this connection. 



In the first tests, a little dry powder of borax, or of sodium fluoride 

 was sprinkled on one-half the bottom of wide, flat, glass-covered culture 

 dishes. Then single roaches were introduced and watched. It was soon 

 noticed that when a roach ran through either the borax or the sodium 

 fluoride, a little of the dry poAvder stuck to the lower part of the body 

 and to the legs — especially at the bases of the legs, and between the 

 sternal plates. Also, the insect was almost sure to get its antennae 

 dusted with the powder as it waved them about. If left to itself, a 

 roach that had become powdered in the manner just described would 

 soon settle down and begin ''cleaning up." In this latter process, the 

 long antennae were drawn across the mouth and licked clean — the feet 

 and legs and body were licked. After a time, a roach that had been 

 cleaning itself of either of the poAvders named would begin to show un- 

 easiness and irritability. It was apt to become sick, after a time, and 

 exude a drop of saliva from the mouth. Finally, the insect would be- 

 come dumpy, often remaining quiet for long intervals, only to start 

 up suddenly and nervously, and then lapse again. Such actions were 

 usually followed by partial paralysis of the hind and middle legs. The 

 wings and feet twitched at intervals, and gradually the body became 

 more helpless until death resulted. This might all take place in any- 

 where from four to forty-eight hours; and the length of time before 

 death would result seemed to depend in great part upon the amount of 

 powder the roach had cleaned from his body. As a rule, the sodium 

 fluoride acted very much more rapidly than the borax — requiring only 

 four to twelve hours. Sometimes a i-oacli that had taken only a little 

 borax, in cleaning the powder from its body, would pass through the 

 first stages of uneasiness (and apparent stomach-sickness) and then re- 

 cover so far as to eat, and act normal for four or five days, perhaps — • 

 after which it would become dumpy. It would then eat no more. The 

 wings would quiver when the insect was disturbed; paralysis of the legs 

 would finally set in, and gradually the body would become more helpless 

 in every case until death resulted. 



Observations were made, and record was kept (from treatment to 



