ECOLOGY

Nectar

Acacia flowers do not produce any nectar. However, the leaf and phyllode glands do secrete a nectar or sugary substance and ants, bees, butterflies and other insects have been observed feeding on these secretions. Honeyeaters have also been reported to use the phyllode and leaf glands as a source of nectar (Keast, Recher, Ford & Saunders 1985). The function of these glands is not clear. They appear to be most productive of secretions when the phyllodes are young or after rain, times when new growth is most abundant and herbiverous attacks are most likely. Many ants (family Formicidae), such as black jumber ants (Myrmecia sp.) and Golden-back ants (Polyrhachis sp.) have been observed feeding on this secretion. The former have also been observed to predate leaf-eating (phytophagus) insects on plants. However, as has been pointed out (New 1984), the ants which may be observed on Australian acacias are more likely to be associated with the taking of the honeydew excreted by some lerps, scale insects and larva of butterflies (family Lycaenidae) than preying on insects and protecting the plant from being eaten. Judging by the amount of leaf and phyllode damage that frequently occurs to acacias, this appears to be the case.

Nectar is sometimes produced during certain times of the day. Insects are often most active during these times.

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