You don’t really consider the identity of the insects responsible in your paper, sorry. You state they are ‘most probably responsible’ and give a single reference. I would have liked to have seen a little more exposition as to how you had ruled out Nicobium castaneum or the various ‘shot hole’ borers (that really do bore directly straight out of timber and are known for attacking fruit trees). If you were writing about risks to the woodblocks changing over time it would be an interesting aside, but postulating a historic geographical species distribution based on one dated text is an over-extrapolation to me. I don’t think you have proved your case.

In terms of block stacking- I was suggesting a difference in storage techniques of the wooden blocks might be responsible for differences in tunnelling pattern. I don’t know have these blocks were stored- but I’d be interested in finding out if there were differences in ambient temperature and if there was a difference in the care given to the blocks.

Hickin’s Insect Factor in Wood Decay is a great reference text. Fig 255, p315 in my copy, pretty clearly shows Anobium preferentially tunnelling along the early wood, rather than meandering across the grain. I think what you have found is genuinely interesting, I just fear the conclusion you have drawn from your data to too much a leap to be presented as fact. Like this:

“I can say clearly that the southern species makes tracks and the northern one doesn’t”

No, you can only say clearly that blocks from southern regions have more ‘tracked’ exit holes. You propose that it’s due to species distribution but don’t back it up.

Anyway. Thanks for responding, it’s an interesting bit of research. I think this should probably go the email from here because I can bore for England if I get started on wood-borers, and will if provoked: em green zero two at gee male dot com Cheers.

If you can’t locate a PDF copy of my article, please email me and I’ll be happy to provide it. The author of the news story was unable to mention all of the details of the study for lack of space. Some points that you make are addressed in the original article. For example, the eggs were certainly laid in the wooden objects, not only post-harvest but post-production of the carved woodblock. In the published supplement I go into detail about criteria used to identify the two species. Besides hole size and shape, they included the type of wood, moisture content, and wood pore size (related to ovipositor size of beetle species).

Yes, I did consider that tracks might be made by beetles exiting stacked blocks, but that would not explain why the tracks essentially don’t exist in the northern species but are characteristic of the southern species. Also, you say that Anobium follows the grain, but the Anobium expert Hickin (1972) page 70 says it “meanders” (i.e., does not follow the grain). Your explanation for following the grain is logical and I suspect that Anobium probably does some of that too. But after examining thousands of wormholes I can say clearly that the southern species makes tracks and the northern one doesn’t (except very rarely). So they are doing something differently. For my purpose that was sufficient because it gave me better discrimination of the northern and southern species, whatever mechanism was responsible for the tracks. It would be a nice experiment for someone to do in the future: to see if Oligomerus ptilinoides larvae actually exit the wood by mistake, or if the tracks are made by adults.

Thank you for your comments!

Ah,
do You know which chemicals were used for that etching process?

They could easily have laid them in the wood post-harvest and those species do, often. As do Ptilinus pectinicornis and other anobiids of about the same size.

“The southern holes also included many long tracks—these were made when the beetles, rather than burrowing straight out, exited from the wood in diagnonal paths that followed the grain.”

That’s one explanation, but it depends on how the blocks are stored. If the blocks are stored on top of each other the larvae would tunnel along the edge of the blocks at the interface giving non-circular exit holes.

Is ‘g’ Anobium punctatum and ‘h’ Oligomerus ptilinoides? I assume so. Anobium tunnels along the grain too- in make no sense at all for wood borers of any species to spend more energy eating low nutrition late wood (high proportion of cell wall, low proportion of cell contents) than early wood with the opposite composition. On pupation some species with tunnel straight out but equally many tunnel along the grain of the wood- because it’s softer and easier to chew through and they expend less energy.

Original is behind a pay wall- I haven’t read it. It’s a nice story, but there some very big conclusive leaps. Which is not to say the conclusion is wrong either but it does smack of fitting evidence to a hypothesis.