THE EGG PARASITES OF THE COFFEE BUG IN KENYA COLONY. 193 



In discussing the data from collections of eggs we may conveniently divide 

 these collections into two lots : — 



A. Those from a field of coffee about six acres in extent on the Government Farm 

 at Kabete. h>om this field a considerable number of collections have been 

 made over a period of two and a half years. Particulars from these collections 

 will be given first. 



B. Those from various other coffee plantations in the districts of Nairobi, Kyambu, 

 Limuru and Thika, but on these plantations usually only a single collection 

 has been made, and that generally at the time of an Antestia outbreak. It 

 will not be necessary to say much about the data from these occasional 

 collections. 



IV. Collections from Government Farm, Kabete. 



Between July 1917 and September 1920 twenty-four collections were made 

 from this field in as many different months. The eggs collected totalled 16,531, and 

 the months in which they were obtained are shown in Table I. 



The chief points brought to light are the following : — 



The average of the monthly percentages of eggs producing Antestia was 15 per 

 cent. ; several times the percentage was 30 or over, while, on the other hand, of 

 more than 5,000 eggs collected between July and October 1917 only 5 per cent, 

 produced Antestia. Of the 16,531 eggs collected during the period indicated, 12,882, 

 or 78 per cent., were parasitised, tfie average of the monthly percentages being 

 practically the same as this figure, namely, 77 per cent. ; the lowest monthly per- 

 centage was 54 per cent., the highest more than 90 per cent. The average monthly 

 percentage of eggs which did not go blue and did not hatch was 8 per cent., and 

 of those eggs which- did go blue 24 per cent, did not produce parasites. Of coffee 

 bug eggs laid in the laboratory and protected from parasites a small proportion 

 did not hatch. Some eggs, too, exposed to parasites in the laboratory turned blue 

 but did not produce parasites. 



The causes of eggs not hatching have not been inquired into. Superparasitism 

 and hyperparasitism, which may quite likely be connected with the failure of 

 parasitised eggs to produce parasites, have not been investigated. 



In the 9,750 parasites that were reared, the proportions of the sexes of the two 

 species were as follows : — 



SS %^c? ?? %?? TotaL 



Hadronotus .. .. 1168 22-6 4009 77-4 5177 



Telenomus .. .. 1079 23-6 3494 76-4 4573 



For both species, therefore, the proportion of females to males was a little 

 greater than 3 to 1. Figures from smaller collections from other plantations also 

 point to a ratio of 3 or 4 to 1. 



The total numbers of the two species have just been given. These give as 

 percentages for the two species : — Hadronotus, 53 per cent. ; Telenomtis, Al per cent. 

 But it must be noted that at those periods when coffee bug eggs were most numerous 

 Hadronotus usually considerably outnumbered Telenomus. So that, if we take the 

 average of the quarterly percentages {see Table I) we then get : — Hadronotus, 43 per 

 cent. ; Telenomus, 57 per cent. Both these pairs of figures, however, indicate that, 

 over a long period, the numbers of the two species in this Kabete field were fairly 

 evenly balanced. 



The variations in the frequency of the two species, for quarterly periods, are 

 shown in Table I (p. 200). We may note : — 



1. The variations are considerable ; sometimes 70 per cent, or 80 per cent, 

 were Hadronotus, sometimes 80 per cent, or 90 per cent, were Telenomus. 



