1913] Determining the Flight of Mosquitos 11 



Mosquito larvae and pupae must be considered as delicate 

 organisms and rough treatment en route makes nil the whole 

 day's work and gives but little encouragement for further work. 



C. The Field Laboratory: The field laboratory is a necessity, 

 but it need not consist of more than a small screened house, 

 about eight feet square, protected from direct sunlight and heat. 

 If located convenient to the breeding places, the collected larvae 

 will suffer but little from jarring en route. Several such houses 

 may be erected at convenient places, however, for all purposes 

 ■one such house will suffice. It means a concentration of the 

 collected larvae at one place and one attendant can give these 

 his undivided attention. No staining of adults should be made 

 .at the laboratory as this would involve transferring of colored 

 adults and the possible escape en route of some of these. 



D. Breeding-out Methods: As soon as the larvae and pupae 

 in the wide-mouthed carrying jars reach the field laboratory, 

 they should be transferred into a large pan. The pupae should 

 be picked out by means of a pipette and confined in jars, these 

 covered with gauze. 



White enameled or porcelain soup plates gave the best 

 results as breeding receptacles for the larvee. If the plates are 

 tilted slightly, both shallow and deep water is afforded to the 

 larvae. Debris and filamentous algae should be reduced to a 

 minimum. The food of the larvae should be known; if diato- 

 maceous, a few pebbles covered with diatoms will suffice. 

 Predacious larvae of all sorts must be eliminated. Some species 

 of mosquitos prefer sunlight, others do not, or there is prefer- 

 •ence for foul water, etc. These peculiarities must be known. 

 Successful breeding depends upon a careful attendance to the 

 peculiar environmental factors of each species. 



Unless the water in the dishes is changed weekly, fouling 

 will ensue and cause heavy mortality. This is obviated by 

 pouring the contents of the dishes over a piece of clean surgical 

 guaze and then inverting over a clean plate containing fresh 

 water. The larvae when in contact with the water will free 

 themselves from the meshes of the cloth. Sudden additions of 

 fresh water were found to be detrimental; best results were 

 obtained with water which had been standing in the room for 

 twenty-four hours. Careful observance to these environmental 

 requirements has reduced mortality among our own larvae from 

 ten percent to less than one percent. 



