MODE OF FEEDING 229 



water images were produced in a normal manner. In a mixture of 19 per cent 

 of sea-water with fresh water only a very small proportion of larvae transformed 

 to images. Beyond this the larvae failed to pupate ; with 20 per cent sea-water 

 some of the larvse survived three days ; with 30 per cent all died after one day. 



HABITS AND FOOD OF THE LARV/E OF ANOPHELES. 



The early stages of Anopheles were first studied in the United States by the 

 senior author in 1899. Eggs were secured from gravid females captured, and 

 the full life round was studied and first described in an article entitled " The 

 Differences between Malarial and Non-malarial Mosquitoes '' in the Scientific 

 American for July 7, 1900, pages 8-9, and subsequently in a bulletin of the 

 U. S. Department of Agriculture. About the same time he found larvae of 

 Anopheles along the borders of a small stream in Eoland Park near Baltimore, 

 Maryland, and was under the impression at the time that he was the first Ameri- 

 can entomologist to find this peculiar larva ; but it seems that 25 years earlier the 

 larva had been found by Dr. Charles Sedgwick Minot, of Boston, and the adult 

 was reared at that time. The identity of the insect was not suspected, however, 

 but Doctor Minot had preserved the early notes, and after the appearance of 

 Bulletin 25 recognized the larva and published an account of his early observa- 

 tions in the Journal of the Boston Society of Medical Sciences, volume v, 

 January, 1901. 



The first reference to the early stages of Anopheles to be found in the litera- 

 ture is a paper by Joblot, published in Paris in 1754 under the title (translated) 

 " Description of a New Fish which I found in the Water of the Basin of St. 

 Magloire of the Fauxbourg Saint- Jaques at Paris, which can be called an Aquatic 

 Caterpillar." He figures the larva, which is recognizable as that of Anopheles. 

 Brauer gave a good figure and description of the larva as that of Dixa in 1883. 

 F. Meinert next published accurate descriptions and figures of the larvae of two 

 European species in 1886. Other descriptions and figures were published by 

 Ficalbi in 1899 and Giles in 1900. The different stages were described and 

 figured in 1900 by Grassi. 



The eggs, elsewhere described, are laid loosely upon the surface of the water, 

 each egg lying upon its side, from forty to a hundred of them as a rule floating 

 rather close to one another. 



The larva, also described in the systematic consideration of the genus, is 

 markedly peculiar in its structure. It habitually remains at the surface of the 

 water. It is without the breathing-tube so characteristic of the other mosquito 

 larvae, and its body is held practically parallel with the surface and immediately 

 below the surface film, while portions of its head as well as its breathing ap- 

 paratus are practically out of the water. In addition to the protruding head and 

 the mechanism surrounding the spiracles the larva is held at the surface by 

 means of rosettes of scales, the so-called " stellate hairs," upon some of the 

 abdominal segments. These protruding parts interlock with the surface film, 

 hence the larva can not descend without an effort and it only does so to escape 

 danger. The larva's head rotates upon its neck in a most extraordinary way, so 



