264 MEDICAL ENTOMOLOGY 



' temperature and the general air-temperature at the time, and that this 

 ' difference must be positive '. 



With our present imperfect knowledge it is not possible to state what 

 other influences may come into play in attracting mosquitoes to bite. 



Many interesting problems, some of them of considerable importance, 

 might be stated with regard to the life history and bionomics of 

 mosquitoes in general and the Anophelina in parti- 

 Some Problems in cukr Qne question is sug gested by the well-known 

 Bionomics , 3 . J . , 



fact that female mosquitoes in captivity can be fed 



and kept alive for some time on a diet of banana, dates, or sugar water. 

 What are the factors which govern their choice of food, and do they only 

 occasionally, or habitually, feed on vegetable juices in addition to blood ? 

 In some regions, as, for instance, certain parts of Greenland, mosquitoes 

 are said to appear in swarms on the advent of a traveller, and to attack 

 him, although previously the region was uninhabited and regular food, at 

 least regular feeds of blood, apparently not available. Are such or any 

 species capable of carrying out their reproductive processes either on 

 a purely vegetable diet or with the aid of the reserve food material 

 carried over from the larval stage, while still retaining the faculty 

 of obtaining and digesting vertebrate blood when the opportunity 

 arises ? 



Perhaps the most interesting question, and the one with the most 

 suggestive possibilities, is that of the choice of host from which mosqui- 

 toes will suck blood. It is well known that certain species will feed on 

 a variety of vertebrates, though it is by no means certain whether this 

 is pure chance, or whether they are guided in their choice in some 

 definite manner ; * in a considerable proportion of cases the blood parasites 

 of mammals are peculiar to one species, and cannot thrive in the blood 

 of another. If a mosquito, or any other blood-sucking arthropod for 

 the matter of that, takes in from one host the infective stages of a parasite 

 which can normally develop in its body, and at the next feed takes in 

 blood from another host which does not harbour this particular species 

 of parasite, will the blood of the second host affect the progress of the 

 cycle of development of the parasite in its invertebrate host ? 



Many other questions will suggest themselves. The above will suf- 

 fice to indicate the necessity for further enquiry. 



Most female mosquitoes may be induced to oviposit in captivity if 

 their eggs are near maturity. When attempting to do this it is best 



* Possibly the difference in the normal temperature of different animals has some 

 influence in the choice of host. 



