I received a comment on an old post from Charmain from Arborviews on the 19th of April, about the bug on the Fig Tree. She identifies it as a Phryneta Spinator – Stem Borer Beetle from South Africa. A real pest!! The larva bore into the fig tree and can actually kill it!! It was uncanny, because that very same day, I was taking photos of my “meadow” for my update and came across weird sawdust pulp at the foot of my Fig Tree. I had not noticed this because of the bark mulch I have around the stem. I was horrified to see what had caused this!
The first person who commented was Denni, she immediately called it the Phryneta Spinator and warned me about the borer larvae – I should have guessed. Thanks!!
This large indigenous beetle of about 35 mm in length has become a serious pest of fig trees in Cape Town. The larvae bore into the wood and in severe cases can eventually kill the tree, particularly if it is old and lacking in vigour. It can also be a pest of Willow trees. The large size, long antennae, mottled appearance and the prominent spines on each side of the thorax make this species easily recognisable. The life cycle takes slightly over three years!
Each egg is laid in summer in a T-shaped slit that the female makes near the base of a branch – from mid-November through to mid-March. The beetles are not usually nocturnal and egg laying seems to only occur during the day. Eggs take 10-18 days to develop (they don’t say how many).
The hatched larva initially feeds on the bark and then later enters the wood and chews its way through the wood, forming tunnels as it does so. This diet of wood is not particularly nutritious and so it needs to eat a lot of wood in order to grow. Larvae are cannabalistic so they tend to space themselves out in the wood, avoiding contact with larvae in other tunnels. The larva packs excrement (‘frass’) and castings behind it as it burrows and pushes some of them through small holes in the bark so that one can often find small heaps of reddish wood fragments at the base of the tree. Larval development takes from 2.7-2.8 years.
Pupa. When fully grown, the larvae tunnel to just beneath the bark where they moult into a pupa. By pupating under the bark, they can make an easy exit when they emerge as adults. The pupal development period lasts 89-99 days. (This could be the stage I found them at, under the bark!)
The adult form develops inside the pupa and on maturity emerges. The female then needs to mate with a male and find suitable sites on host plants for laying her eggs.
Referenced from http://www.biodiversityexplorer.org/beetles/cerambycidae/phryneta_spinator.htm