Leaf Blisters and Leaf Mines

leaf blistersleaf miner damage

Leaf blisters (photo 1) and leaf mines (photo 2) are caused by the feeding activities of insects with chewing mouthparts. Feeding occurs on the mesophyll, located between the upper and lower leaf epidermis and as the insect feeds, the leaf is hollowed out. Consuming leaves this way is often an excellent means of protection for the insect, as it is able to feed while remaining hidden from predators.

Leafblister sawfly larvae commonly cause leaf blisters on eucalypts as a part of their life cycle. The female lays her eggs inside the mesophyll tissue of a eucalypt leaf and following hatching, the larvae consume the tissue that surrounds them, leaving the epidermis intact. As the larvae grows, it consumes more of the leaf and the blister increases in size - sometimes joining the blisters formed by other larvae on the same leaf. When the larvae pupates, it does so within the blister and adult wasps emerge from it.