Lerps

Let’s talk lerps. Such a funny word. Lerp. Reminds me of Lurch from the Addams family, but Lurch was huge (6 ft 9 in apparently) and lerps are small. Not quite as small as the psyllid nymphs that make them, but still pretty small.

I should start from the beginning though because you may indeed not know what a lerp is. A lerp is a sugary secretion produced by the immature form of psyllids or jumping plant lice. Psyllids are closely related to scale and are tiny, winged, sap sucking insects. The nymphs of some psyllids excrete honeydew and make a waxy scale-like shell to shelter under and feed. What’s more, lerps are nearly exclusively native to Australia and found on our gum trees. Indigenous people collect them as a sweet treat and source of energy, and early European settlers learned to do the same. I haven’t brought myself to eat psyllid poop yet but I suppose I’m not against it and will one day get caught by a neighbour picking white flecks of my verge tree and eating them…

The psyllid nymph is the tiny lemon coloured crawling insect. If you look closely you can see them under the more clear lerps. I believe the opaque lerps are empty.

On the whole, despite sucking the sappy goodness from your gum trees, the lerps are more unsightly than anything else, but if you have a really heavy infestation, it can cause leaf defoliation (like my verge tree!). The nymphs do most of the damage, and because of their sweet honeydew coverings, ants like to farm them, which can deter natural insect predators. Putting a band of horticultural glue around the tree trunk can prevent the ants coming up.

Because my verge tree is small, I have had some success spraying with neem oil which helps smother those insects that aren’t under their protective sugar shell, and washes off some of the excess honeydew. It’s only a temporary solution and impractical for larger trees or ongoing treatment but at least I have a few leaves for now. The best way is to let nature take it’s course and make sure your tree is as healthy as it can be. I am yet to work out what the problem is with mine - most sources suggest plants may be lacking moisture but I did have a theory that mine was sitting in a bowl of water in my clay sub soil. Investigations to be had!

The damage the psyllids leave. The worst leaves turn completely brown and fall off, leaving a very twiggy tree.

In addition to insect predators of the psyillds (wasps, beetles, other larvae etc etc, depending on the species) there are also a lot of birds, and even flying foxes and gliders who have clued on to the sugary lerps, so if you want to attract a range of wildlife, it’s best to leave some be!

My Corymbia ficifolia. This is why I’m putting in so much effort to try to keep her happy!