Published online by Cambridge University Press: 10 July 2009
1. The paper describes work carried out to find the causes of certain discrepancies in the results of longevity experiments on rat-fleas.
2. The following factors were found to reduce significantly the survival period of unfed adult fleas:—
Rearing larvae together rather than in separate tubes; Parent fleas over 11 days old; Using very fine rather than coarse sand as a matrix for larval food; Drying the blood for larval food by baking rather than in a vacuum over sulphuric acid at room temperature.
3. The following factors were found to have no significant effect upon adult longevity:—
Contamination of larval food by mice and their droppings;
Presence or absence of adult flea faeces in larval food.
4. The effect upon the weight of larvae and the duration of the larval period of some of the above-mentioned factors is described. The female larval period is shown to be shorter than that of the male under all conditions used.
5. It is confirmed that there is no significant difference between the longevity of male and female adults which have fed once or not at all, and that females which have fed frequently before starvation live longer than males.
6. Well developed, unfed, laboratory-bred adult fleas live longer than those which have fed once before starvation, and the latter live longer than those which have fed several times.
7. There is some evidence that unfed wild-caught fleas live longer than wildcaught fleas which have fed, but this needs confirmation.
8. All the available information regarding factors affecting adult longevity is summarised in a table.