44 MP., r. p. HARDtNBERG 



Proportion of the sexes, as indicated bv the pupae: — 

 (A), males 28%, female 5%. 

 (B). males 25%, females 20%o. 

 (C). males 40%, females 25%^. 

 Parasites:— (A). 52%o; (B).9%; (C). 19%. 

 Fungus disease.— (A). 3%; (B) 18%; (C) Z%. 

 Other diseases.— (A). 10%, (B). 33%, (C). 10%. 



Thus we find the mere presence of large wattle planta- 

 tions has the following effects: — 



(a). Producing more vigorous individuals, on account 

 of the unlimited food supply. This in turn favourably 

 atfects the reproducton, as the number of eggs laid by one 

 individual depends entirely upon its size and vigour, 

 ranging from about 150 to 3,000. 



(b). A decrease of parasitism. The parasitic wasps 

 and flies are lovers of sunshine and have better access 

 to the bags on the isolated thorn ti*ees than inside the 

 large blocks of wattle trees. 



(c). To balance this there is an increase in the number 

 of bagworms killed by fungus and disease, but this be- 

 comes only apparent after successive generations of bag- 

 worms in the same plantation. In the young plantation 

 (C), where the canopy has not yet been formed and thQ 

 conditions thus approach those found in the thornveld, 

 with the exception of the unlimited food supply, the per- 

 centage of diseased and of parasitised individuals is 

 approximately the same as in the thornveld. 



Tt is also most probable, but no definite data have been 

 secured, that the insectivorous birds, known to prey on 

 the bagworm are also less numerous inside the planta- 

 ticms than outside, which would favour the increase of 

 tlie insects still more. 



There is yet another jmint to be considered. Om 

 account of the destruction of the native vegetation many 

 other insects, usually living on the grass and low her- 



