Insects dissected and reared from the fruits of four species of Leptospermum (myrsinoides, juniperinum, laevigatum and lanigerum), three species of Eucalyptus (baxteri, obliqua and willisil] and four species of Casuarina (pusilla, stricta, littoralis and paludosa), collected from 18 sites over four seasons at Wilsons Promontory in south-eastern Australia, are enumerated and discussed. Fruits of all species supported abundant and diverse assemblages of seed-eating insects and associated parasites. The distribution of phytophagous insects was related to host-plant phylogeny and, in particular, to fruit morphology. When fruit morphology was relatively constant within a host-plant genus (Eucalyptus and Casuarina), that genus supported a characteristic suite of seed-eating insects; when it varied markedly between species (Leptospermum), so did the composition of seed-eating insects. Insect species often occurred widely within a host genus, but were never recorded from different host genera. An extensive radiation of seed-eating Anobiidae (Dryophilodes spp.) in myrtaceous capsules parallels that of weevils known in fruits of Acacia. The major seed-eating insects recorded in each host taxon were: (a) in Eucalyptus spp. (all fruits woody and persistent capsules), Dryophilodes sp. B (Coleoptera : Anobiidae) and chalcidoid wasps, mostly Megastigmus sp. (Torymidae) and Eurytoma sp. (Eurytomidae); (b) in Casuarina spp. (all fruits woody and persistent 'cones'), chalcidoid wasps, mostly Bootanelleus sp. (Torymidae), and unidentified cosmopterigid moths; (c) in Leptospermum juniperinum and L. lanigerum (woody and persistent capsules), Dryophilodes spp. C and D, and unidentified cosmopterigid moths; (d) in L. laevigatum (semi-fleshy and semi-persistent capsules), Dryophilodes sp. E and an unidentified cecidomyiid fly; (e) in L. myrsinoides (fleshy and ephemeral capsules), an unidentified weevil and unidentified carposinid moth.