Scribbly Gums led me back to "Old Tom" Greaves.

The Scribbly Gums of Tourist Road, Kangaloon have led me to a discovery about an old acquaintance of mine, from Canberra days - Mr Tom Greaves.

Scribbly Gums on Tourist Road, Kangaloon.

These scribbles are the work of the larvae of tiny moths in the Ogmograptis genus. The larvae hatch from eggs laid in crevices in the bark of certain species of Eucalypt trees. The larvae burrow under the outer layer of bark, and eat their way around underneath that layer of bark, leaving their tracks as tiny scars on the inner layer of bark. This is only apparent when, in the next season, the old bark is shed (as in the lowest photo).

Patterns on the bark
trace the path of the moth larva

There is always a pattern to the marks left by the moth larvae. It starts out as a very thin line, (see the lowest part of the photo above). Then the line suddenly appears to have got much fatter. In fact, if you follow the line along (its original course) you will find a loop (at top-right, in this image). At this point the moth larva turns around, and retraces its path, coming back beside its original line. It is that which makes the track appear fatter than at first. Half-way back the thick track stops. That is where the moth has reached maturity. It eats its way out of the protective covering of outer bark, and escapes to the outside world, drops to the ground, and forms its chrysalis there. Eventually a moth hatches out - flies, mates and dies. Female moths will lay their eggs on the bark of their favourite species of Eucalypt tree - and thus the cycle repeats.

The mysterious scribbles on the Scribbly Gum were written about by the famous Australian poet, Judith Wright - as quoted on this CSIRO Fact Sheet.

I learnt today that the mystery of the scribbles on the Scribbly Gums was first discovered by a CSIRO scientist, Mr Tom Greaves, back in the 1930s. The Latin name Ogmograptis scribula was ascribed to the first specimen identified. The name means the "Scribe who writes".

This information is very personal, to me, because I have just realised that I knew Tom Greaves, in his retirement, in Canberra. He was a neighbour of a good friend of mine, who lived in Reid, in Canberra in the 1980s. "Old Tom" (as he was known affectionately) was renowned for giving away the surplus vegetables which he grew in his highly productive backyard vegetable garden. He was a fanatical vegie grower, and his yard was exceedingly well organised. He delighted in showing it to visitors, and I had the honour of being shown around it by "Old Tom" himself. His compost heap was his pride and joy.

I now recall that Tom Greaves was the author of the Vegetable Growing section of one of the early editions of "The Canberra Gardener", published by the Horticultural Society of Canberra. My father gave me a copy of that book when I bought my first house, in 1972.

*****

I learnt about the Scribbly Gum Moth about 10 years ago, when I became a volunteer guide at the Botanic Gardens in Canberra (ANBG). But I did not know about the connection to "Old Tom" until I read this report today. I recognised his name as "familiar", but it took a while for my grey matter to sift through its databases - then "bingo" - I realised that I knew Tom Greaves, in very different circumstances from those in which I have come across his name today (as an entomologist).

Old bark peeling off, revealing the next layer of scribbles.
Next year's marks will be made (out of sight) under the fresh bark layer.

Post script: "Old Tom" died one day, probably in the early 1990s, in a neighbour's kitchen - where he had gone to share some of his vegetables. "Old Tom" was thoroughly respectable, but you will not be surprised to learn that tongues wagged for weeks, in the neighbourhood. Personally I always thought that it was the ultimate way for an old Vegie Gardener to go - sharing his surplus produce with friends.

I prefer to remember Old Tom as a wonderful generous soul, a Vegetable Grower, par excellence, and now, as the discoverer of the Scribbly Gum Moth.