136 STATE BOARD OF AGRICULTURE. 



for its excursions. It is the members of the genns Anopheles that carry 

 malaria. Of course the insect will not produce the disease, it can only 

 carry it from individual to individual when once present. 



The practical methods of fij^hting mosquitoes may be class^ed under 

 three heads, viz.: Draining; introducing fish, which are known to feed 

 on the wigglers, into Ashless ponds; and spreading oil upon the sur- 

 face of their breeding places. Of these three, the first is of course the 

 most permanent and effective. It can not be otherwise than perfect 

 since it destroys the breeding places and therefore the mosquitoes. 

 The second method — introducing fish into the breeding places — seems 

 more of a palliative measure than one which will result in extermina- 

 tion. The third method — spreading oil on the breeding places — is the 

 most expensive of the three, although it is almost as certain as the 

 first. The oil forms a thin film on the surface of the water and coming 

 in contact with the breathing tubes, kills the wigglers, as it kills 

 almost all insect life. The field work in the present experiments was 

 done almost entirely by Mr. Bronson Barlow, and it was owing to his 

 efficient work and careful notes and observations that the work was 

 rendered possible. 



An area of four square miles was at first laid out as a basis on which 

 to work. A map was made on which was indicated so far as possible 

 all the breeding places of the pests, and records of each treatment were 

 carefully set down. 



On April 21st, such ponds as would not be injured by oil were treated 

 with a coat of petroleum oil, known as light fuel oil. This spread over 

 the surface and in a few hours killed all the mosquitoes, both in the 

 larval and in the pupal stages. The oil is that recommended by Dr. 

 Howard. It cost about $4.50 per barrel here at the College and was 

 applied at the rate of one-half gallon to one thousand square feet of 

 water space, or one ounce to fifteen square feet. This amounts to 

 about half a barrel to an acre. It was applied by means of a knap-sack 

 spray-pump fitted with a plain nozzle, that is a nozzle having a hole 3-32 

 of an inch in diameter. With this it was possible to throw the oil 

 twenty feet or more in a solid stream and thus to reach far in toward 

 the center of a pond. Actual counts showed the number of wigglers 

 to be as large as 900 to a square foot at this time, in small areas. 



Many surprises await the person who tries to exterminate mosqui- 

 toes. Hollows, made by the breaking ofif of limbs, were found to furnish 

 fine homes for mosquito families. Rain-barrels, sometimes furnish 

 unheard-of numbers. Pools in the woods, drains, open cisterns, and 

 cisterns not tightly screened, watering troughs, in fact almost any- 

 thing that will hold water and which is not expbsed to too much wind, 

 will keep them. The ideal places in this vicinity were found to be 

 swales with cottonwoods or willows standing in them. Another likely 

 place was found in poorly-drained woodland. Woodland ponds were 

 likely to be pretty well stocked with the malarial mosquitoes. Ponds 

 covered with green water-scum often harbored the malarial species, 

 and in such places fish work at a great disadvantage, the larvae being 

 very successful in hiding away. 



PISII. 



Dr. Howard highly recommends the introduction of small sun-fish 

 and stickle-backs in places where they may be expected to live. Sev- 



