LABORATORY METHODS IN MALARIA 367 



twine lengthwise on a long strip of adhesive tape. The tape, cov- 

 ering the twine, is then placed around the cage. A hole is made in 

 the bobinet at one end for putting in or removing mosquitoes. This 

 opening may be plugged with cotton. 



Mosquitoes emerging from a collection of pupae are conven- 

 iently got into a cage in the following manner : Place the pupae with 

 water in a tea cup or similar receptacle and upon it set a lantern- 

 chimney cage from the lower end of which the bobinet has been 

 removed. The rim of the cage must fit the cup closely. As the 

 mosquitoes emerge they will fly into the cage. When a sufficient 

 number have entered, remove the cage and replace the bobinet. 



Mosquitoes will soon die unless they are fed. If a suitable 

 gametocyte carrier is available they may be fed on him the day 

 after their emergence. Some species bite well on the day they 

 emerge, but usually feed much better a day later. But suitable 

 gametocyte carriers are not found every day and may not long 

 continue to carry gametocytes in sufficient numbers for infection. 

 Therefore, unless one has a prolific and convenient breeding place 

 of Anopheles available, it may become necessary to keep adult 

 mosquitoes in stock while awaiting a suitable carrier. A batch may 

 be kept alive and in good condition for long periods by feeding 

 them every four or five days on a normal human subject or a 

 laboratory animal. It is advisable to have several batches on hand, 

 feeding them on different days so as to have a hungry batch ready 

 in case a carrier is found. In summer weather mosquitoes bite well 

 about two days after a blood meal and may then be used on a 

 carrier. 



Method of feeding mosquitoes on a carrier. It is a good plan 

 to moisten the skin of the patient before the cage is applied. The 

 cage may be placed on the arm or any part of the body of the 

 carrier. He may be persuaded to hold the cage in his hands with 

 the palms in contact with the bobinet at both ends. Most Anopheles 

 bite well, especially if strong specimens are used and are allowed 

 to get thoroughly hungry before feeding. They usually bite bet- 

 ter if deprived of their water supply some hours before feeding 

 and allowed to get thirsty. Sometimes one can stir up the less 

 eager specimens by breathing into the cage. Anopheles can be fed 

 at any time during the day. 



The conditions of some experiments require that mosquitoes be 

 fed but once and only those which have taken blood be dissected. 



