Various species of insects, especially coccoids (Hemiptera) form distinctive galls on Casuarinaceae; some of these may be mistaken for fruiting cones but they are actually modified vegetative branchlets. Coccid galls also affect eucalyptus species. They are a group of sap-sucking insects whose saliva stimulates plant cells to grow in such a way as to form a gall that looks somewhat like the fruit of the allocasuarina. Control is usually unnecessary, but removing young galls from the plant may reduce future infestations.
Above is a photo of a psyllid gall on the same allocasuarina species in the Domain near the Botanic gardens.
Ref : Judy McMaugh, pg 148, Australian National Botanic gardens website.
These are sometime confused for the seed baring cones of the Allocasuarina. Fairly common on Allocasuarina verticillata
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