THE EGG PARASITES OF THE COFFEE BUG IN KENYA COLONY 



195 



only 5 per cent, of the eggs collected produced Antestia, more than 85 per cent, 

 being parasitised. Since then — up to the end of 1920 — the bugs have never been 

 at all plentiful there. 



The parasites are sometimes present in force in plantations where there has never 

 been a coffee bug outbreak. The following figures are for a field of coffee about 

 three years old, when the collection of eggs was made where there had never been 

 an outbreak : — 



The usual state of affairs in coffee plantations, it may here be remarked, is that 

 Antestia exists in small numbers only, but if the bug was present in a plantation, 

 parasitised eggs have always been found when a search has been made for them. 



There are several cases on record when one outbreak of Antestia that has been 

 controlled by collecting the bugs by hand has been followed by another after some 

 such period as two years. 



From some collections, notably from the Limuru district, Hadronotus has been 

 completely absent, though a very small number of Hadronotus have been reared 

 from eggs from one Limuru plantation. Telenomus has been reared from every 

 collection examined. 



VL Life-history Work on the Parasites. 



Many of the facts here given have already been published in Mr. Anderson's 

 bulletin. 



A. Hadronotus antestiae. 



(1) Length of Life of Parasites. 



For parasites kept in tubes closed with a pad of dry cotton-wool, provided with 

 water on a pad of cotton-wool moistened daily, and with coffee bug eggs in the 

 tube, the average length of life for either sex was about six days. 



Five unmated females kept singly in tubes, provided daily with diluted golden 

 syrup on a pad of cotton- wool and supplied with coffee bug eggs, lived on the average 

 13 days. Further data for parasites which did not have access to coffee bug eggs 

 have given a slightly shorter time. The longest life of a female recorded is 16 days, 

 that of a male 13 days. 



(2) Life-cycle of Parasites ; Mated Females given Water only. 



A series of experiments, in which the conditions defined below were adhered to, 

 was designed to compare the reproductive powers of the two species. The facts 

 for Telenomus will be given when the life-cycle work on that species is described. 



The conditions were as follows :— (a) The experiment was set going not earlier 

 than 22.xi.17 and not later than 21 .ii.l8 ; (&) all parasites used as parents had emerged 

 from the coffee bug egg on the day on which the experiment was started ; (r) all the 

 parasites used were known to be virgin, as they had emerged in tubes not containing 

 any individuals of the opposite sex ; (d) the act of copulation was observed to take 

 place ; {e) once a parasite, male or female, had mated, no individual except its mate 

 was allowed access to it during the remainder of its life ; (/) the parasites were given 



