REPORT ON MOSQUITOES. 6i 



original mixture of six ingredients, but the amount of narcotic herbs con- 

 tained therein was very small ; the insects quickly revived after the smoke 

 had disappeared and I was compelled to prepare a stronger mixture, to the 

 fumes of which at least go per cent, of the insects fell victims. In cellars 

 number 9 and number 15 a strong mixture was employed with gratifying 

 results, especially in number 15 — this veritable bee-hive of hibernators. The 

 result was beyond expectations. 



In a cellar at Elizabeth I employed in one compartment chenopodium 

 seeds, in the second compartment a mixture of chenopodium and stra- 

 monium and the third compartment stramonium only. The result was the 

 following : In the first compartment the mosquitoes were found alive ; in 

 the second and third compartments they were found stupified. I visited 

 the same place again four days after and found a number of dead insects 

 in compartments 2 and 3. Unfortunately, I found the doors connecting 

 these several parts of the cellar open, and whatever live mosquitoes had 

 remained in the place were to be found in compartment 3, the darkest and 

 most moist in the whole place. Wherever I used stramonium fumigating 

 piowder it was mixed with saltpetre in the proportions of three parts of 

 drug to one of saltpetre. In order to produce the desired effect the cellars 

 should be closed as tightly as possible, so as not to give the fumes a chance 

 to escape. Spread the powder on a large piece of tin in a layer of, per- 

 haps, not more than on-half an inch and, if the cellar area is a consider- 

 able one, use several of these tins. Ignite the powder on several ends in 

 order to hasten process of combustion. It is absolutely necessarj^ to keep 

 the cellar tightly closed during a period of, at least, two hours. The 

 smoke by this time will have partly disappeared, leaving no disagreeable 

 odor. The quantity of the above-named mixture used in a space of i.ooa 

 cubic feet is about eight ounces, which can be readily purchased at a whole- 

 sale druggist for about forty to forty-five cents a pound. In the latter part 

 of my investigation I tried one experiment which I like to mention in this 

 report. I have shown before that in cellars number 22, 23 and 24 the ab- 

 sence of mosquitoes was due to the presence of carbonic acid gas. The 

 cheapest and most economical way of preparing this gas is by the burning 

 of charcoal in an open furnace. The gas which is produced first, car- 

 bon monoxide, is somewhat lighter than air and will be found to rise to> 

 the upper portion of the cellar, but it soon will associate itself with suffi- 

 cient oxygen to form a heavier gas — carbon dioxide, or carbonic acid gas. 

 I have killed several mosquitoes in a very short time by placing a tiny 

 furnace in my experimental chamiber. Air (oxygen) was admitted to the 

 furnace by means of a rubber tube, to which a rubber bulb was attached, 

 keeping the charcoal in a continual blaze. This is a very cheap method, 

 costing not more than fifteen to twenty cents for a cellar of even large area. 

 The cellar should be closed tightly, the furnace or furnaces placed in a 

 secure position, so as not to come in contact with any inflammable mate- 

 rial. We know that this gas formed in the aforesaid manner is a dan- 

 gerous one to the human organism, but not nearly as dangerous as the 

 fumes of hydrocyanic acid, which have been recommended to kill insects 

 and vermin of all sorts. Every person is accustomed to the use of charcoal 

 and, knowing what effects the fumes have on the physical makeup, can 

 readily guard against any fatality. 



Before closing, there is one other point regarding the extermination of 

 hibernating mosquitoes that might be of interest. My report shows that 

 the insects were found not so numerous in cellars that were thoroughly 

 whitewashed. Up to this date I cannot account for this occurrence. Vari- 

 ous theories have been advanced by some of my acquaintances who have 

 taken an interest in my investigation. Some of them said, and I at first 

 thought it worth while noting, that the whitewash might have a poisonous 

 effect upon the insects ; others again maintained that the whitewash ren- 

 dered a cellar light, and as the insects preferred to hibernate in dark places 

 a ready explanation would be found in their theory. I tried a simple experi- 

 ment. A one-quart jar was taken and the inner walls thoroughly white- 



