298 



CONTROL OF WATTLE BAG WORM. 



given below, Haines' records probably refer to more than one 

 species of parasite in each case, but the records collected by 

 myself refer only to the two parasites mentioned above. 



Date. 



Locality. 



No. of Bags 

 Examined. 



Dipterous 

 Parasitism. 



Hymenopterous 

 Parasitism, 



Collector. 



April-Sept , 

 1914 ... 



June. 19H) 



Mar.-Oct., 



idk; ... 



Mar.-June, 

 1920 ... 



Mar.-June, 

 1920 ... 



Mar.-June, 

 1920 ... 



Clan Syndicate 

 Baynes Drift ... 



New Hanover 

 Mountain Rise 

 Hilton Road ... 

 Town Hill ... 



17.742 

 ()(t0 



l(),34.j 



12.700 



sou 



n.-ioo 



No. 



2.84S 



334 



Per cent. 

 IC. 



No. Per cent. ' No. Per cent. 



900 .")■.') 2.85K 17T. 



(;29 



10 



3S.-, 



1-2.-) 

 3 3 



1 ,8(1.". 



Hi 2 



1,379 12 



147 



Haines. 

 Haines. 



Haines. 

 Skaife. 

 Skaife. 

 Skaife. 



Totals 



41.34: 



1 ,924 



4-7 



G.llS 



14-K 



The above figures show that an average of about 20 per 

 cent, of the bagworms that survive the early perils of their 

 life are destroyed by insect parasites, but they also show 

 that this percentage varies greatly in the dift'erent localities. 

 This variation seems to have a direct relation to the degree of 

 infestation of the plantations in which the insects vk'ere found. 

 At Hilton Eoad, where the infestation was very slight and it 

 was difficult to collect any number of bagworms, the parasi- 

 tism Avas only just over 3 per cent., whereas at Mountain 

 Eise, a heavily infested plantation, nearly 20 per cent, were 

 parasitised, the figures also show that the hymenopterous 

 parasites are more than three times as efficient as the tachinid 

 parasites. 



Diseases. 



The fungous disease of the bagworm, caused by the para- 

 sitic fungus, Isaria psychidae, Pole Evans, is well known 

 owing to the researches of Dr. Pole Evans, who studied this 

 disease and initiated some preliminary experiments in its 

 artificial dissemination. Owing to pressure of other work. 

 Dr. Pole Evans was unable to follow up his studies, and the 

 work was taken up at Cedara. The results of observations 

 made during the past eighteen montlis will be embodied in a 

 later paper. The efficiency of this higlily virulent fungus as 

 a check on the bagworm is somewhat impaired by the attacks 

 of a secondary parasite, another fungus known as Mclanospora 

 parasitica. The Melanospova grows upon the Isaria, and 

 partially or wholly inhibits the conidia formation of its host, 

 thus curtailing the spread of the disease. 



Another virulent and highly destructive disease of the 

 bagworm is caused by a filterable virus, and is very similar in 

 its nature to the " polvederkrankheit " of silkworms and nun 



