Mosquitoes and Malarial Fever 519 



After having deposited the first lot of eggs, the female is ready to feed 

 again and produce a new lot. This can go on for a number of broods. 

 How long the insects can live, probably depends upon their activities. 

 When actively engaged in reproductive activities they probably 

 live a shorter time than when hibernating or estivating. It is known 

 that some of them can live the greater part of a year. 



The mosquitoes used for study and for classification should be 

 mounted dry in the usual way well known to all entomologists. 



Fig. 197. — Imago of Anopheles maculipennis escaping from the pupa case upon 

 the surface of the water (Brumpt). 



Fine entomologic pins (oo-ooo) should be employed for the purpose. The 

 insects should be caught in a wide-mouth bottle containing some fragments of 

 cyanid of potassium, covered with a layer of sawdust, over which a thin layer of 

 plaster of Paris is allowed to solidify. The insects die in a moment or two, can be 

 emptied upon a table, and the pin carefidly thrust through the central part of 

 the thorax. As soon as the insect is impaled, the pin should be passed through an 

 opening in a card or between the blades of a forceps until the insect occupies a 

 position at the junction of the middle and upper third. The insect should not 

 be touched with the fingers, as the scales will be brushed off and the limbs broken. 

 Mounted insects must be handled with entomologic forceps, touching the pins 

 only. Every insect thus mounted should have placed upon the pin, at the junc- 

 tion of the middle and lower thirds, a small bit of card or paper, telling where and 

 when and under what circumstances it was taken. 



The dissection of fiesh mosquitoes for determining whether or not they are 

 infected with malarial organisms must be made with the aid of needles mounted 

 in handles. The position of the stomach, intestines, and the salivary glands, and 

 the mode of pulling the insect apart to show them can be learned from the dia- 

 gram. The organs thus withdrawn and separated from the unnecessary tissue 

 can be fixed to a slide with Meyer's glycerin-albumin or other albuminous matter, 

 and then stained like a blood -smear, but should be cleared after staining and 

 washing, and mounted in Canada balsam under a cover-glass. 



A more certain and more elegant manner of showing the parasites in infected 

 mosquitoes is by pulling off the legs and wings, embedding tbe insect in paraffin 

 and cutting serial longitudinal vertical sections. 



To idect mosquitoes and study the development of the malarial parasites in 

 their bodies, the insects should be bred from the aquatic laiva in the laboratory, 

 to make sure that they do not already harbor parasites. The mosquitoes are 

 allowed to enter a small cage made with mosquito netting, and are taken to the 

 bedside of the malarial patient, against whose skin the cage is placed until the 

 insects have bitten and distended themselves with blood, when they are taken 

 back to the laboratory, kept as many days as may be desired, then killed and 

 sectioned. In this way, remembering that the entire mosquito cycle of develop- 

 ment takes about a fortnight, any stage of the cycle may be observed. 



