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THE AUSTRALIAN MUSEUM MAGAZINE. 



The Use of Australian Fig Trees and Their 



Associated Fig Wasps in Reafforestation 



Work in the Hawaiian Islands. 



By C. E. Pemberton {Assistant Entomologist, Haicaiian Sugar Planters" 



Association.) 



RESIDENTS of Australia, familiar 

 with the Moreton Bay Fig tree, 

 Ficus niacrophylla, and the Port 

 Jackson Fig, Ficus rubiginosa, will be 

 interested in the progress of a reaffores- 

 tation project now in operation in the 

 Hawaiian Islands, wherein these two 

 splendid trees are being particularly 

 utilized. 



In December, 1920, the writer was 

 detailed to Australia to study and intro- 

 duce these and other Australian trees 

 of the genus Ficus to Hawaii. A few 

 fine specimens of both Ficus macro- 

 phi/Ua and Ficus rubiginosa were already 

 growing in Honolulvi but had never 

 produced fertile seed and could not 

 hence be used as mother trees for ex- 

 tensive planting. The prime object of 

 the visit was to obtain quantities of 

 fresh seed of these trees, and particu- 

 larly to ascertain precisely why such 

 trees produce viable seed in Australia 

 but not in HaAvaii and elsewhere where 

 a few have been planted. 



Both the Moreton Bay and Port 

 Jackson Figs produce fertile seed in and 

 about Sydney. Through the courtesy 

 of Mr. .1. H. Maiden, Director of the 

 Sydney Botanic Gardens, the privilege 

 was obtained to pursue a study of the 

 problem and collect seed of these trees 

 in the Sydney Gardens and Domain. 

 BrieHy summarised, the results of this 

 Avork were as follows. 



The Moreton Bay and Port Jackson 

 Figs Avere found to produce fertile seed 

 only thrt)ugh the agency of ceitain 

 minute insects Avhich act as pollinators. 

 Each type of fig tree has its particular 

 fertilizing or pollinating species of 

 insect. The insect peculiar to the 

 Moreton Bay Fig occurs in its fruits, 



Pleistodontes froggatti, the Moreton Bay Fig 

 Wasp, magnified about twenty-tliree times. 



[A(iJ-ic. Ga:ette. X.SAV . 



pollinates the minute fioAvers Avithin 

 the fig in the manner described beloAV 

 and liA^es tightly enclosed therein during 

 all but a fcAv important hours of its 

 nine to tAvelve Aveeks of life. This 

 insect Avas not found in the fruits of 

 any other tree, plays no part in the 

 development of seed of any tree other 

 than the Moreton Bay Fig, and natur- 

 ally has dcA^eloped or evoh^ed into its 

 oAvn peculiar form coincidentally with 

 the dcA^elopment of this tree in the 

 coastal regions of Ncav South Wales 

 and Queensland, AA'here it is indigenous. 

 The placing of fine cloth gauze OA^er 

 branches bearing small figs just form- 

 ing, prcA'ented the fig-insects from 

 reaching them, and in cA^ery case no 

 fertile seed de a eloped. Other figs, so 

 screened, but given one or more of the 

 fig-Avasps, developed perfectly and con- 

 tained fertile or germinable seed. 

 Moreton Bay Fig trees planted by man 

 in Melbourne, Ncav Zealand and Fiji, 

 Avhere the tree is not natiA^e and AA'here 

 the particular fig-insect aboA-e men- 

 tioned does not occur. Avere examined. 

 No fertile seed dcA^elops on the trees 

 in these localities. The reason is 

 CA'ident ; the necessary pollinating 

 insect is not there. If it has CA^er 



