Gl 



Blacklock (Dr. 1*.). On the resistance of Cimex Jectularius to 

 various reagents, powders, liquids, and gases. — Ann. Trap. 

 Med. Pamsit., vi, no. 4, 80tli Dec. 1912, pp. 415428. 



The author remarks that in many cities and villages, the bed- 

 bug- is more or less tolerated as being- at least a harmless creature, 

 although recent investigations tend to show that this is tar from 

 being- the case. A position of safety appears to be a matter of 

 prime consideration to the insect, and being- a very rapid walker 

 it is able to take shelter at a considerable distance from its feed- 

 ing- ground. Thus iron bedsteads, though a great advantage, 

 are not in themselves a suificient means of dealing with the pest. 

 Unlike ticks, the bed-bug does not take a long time to feed. It 

 runs rapidly from place to place, halting here and there for a 

 few seconds to suck blood. Bugs can subsist for a long time 

 without food; they have been kept alive in the laboratory for 

 three months easily in a test-tube fitted with a cork; they will 

 even moult under these conditions. 



Simple methods of obtaining the eggs of bugs are given, 

 together with the author's observations as to the period of incu- 

 bation, which he found to be, on an average, seventeen days at 

 the laboratory temperature, of June, July, and August; fourteen 

 days at 22° C, and 10 days at 25° C. Twenty-four hours immer- 

 sion in cold water prevented them from liatching. The larvae 

 begin to feed within a hour or two of emergence, and in order to 

 feed them safely the shaved skin should be as dry as possible, 

 otherwise the antennae and legs become glued together and they 

 die. The larvae are not capable of resisting- much heat; 150 

 unfed larvae have been known to die within five minutes on being- 

 exposed to a temperature of 45° C. ; the adult bug can resist this 

 temperature somewhat longer. 



The author tested the effect of powders, {a) by placing the bugs 

 in a clean " petri dish," and sprinkling the powder over them; 

 (6) by sprinkling the powder over the dish, and then placing the 

 bugs in it ; (c) by making a ring of powder in the bottom of the 

 dish a quarter of an inch wide, with an open centre as large as a 

 five shilling piece, and the powder a sixteenth of an inch deep ; 

 the bugs were placed in the centre of the ring, and any that 

 passed through it were collected and placed in a clean dish for 

 observation ; (d) an island of powder was placed in the centre of 

 the dish, and the bugs outside it, those which touched or walked 

 through the powders and regained the clear area being- examined ; 

 {e) same as {d), but pieces of blotting-paper were placed in the 

 dish to shelter the insects. 



Experiments on eggs were made by placing them in powder 

 for an hour, then removing them and placing- them in small 

 capsules. Other eggs were placed upon a layer of the powder 

 under trial on the bottom of the dish, and the effect on hatching 

 observed. 



The following is a list of the powders tested : Keating' s, 

 Hawley's I.K., Danzo Powder, Cimo Bane, Jacko Dust, Yal's 

 Beetle Cure, and Steiner's Genuine Dalmatian Insect Powder. 



(SiKlCO— 2.) Wt. PI 1—12. 2000. 4/13. D & S. 



