How Much Wood Could a Wood Beetle Chew, If…

The tree is more than first a seed, then a stem, then a living trunk, and then dead timber. The tree is a slow, enduring force straining to win the sky.

~Antoine de Saint-Exupery

Last week I cut and split some firewood from a hickory that fell across the road in the storms of October, 2018. The wood has been stored under a tarp (with sides exposed) since that time. When I pulled the tarp off to start cutting, I immediately noticed the many piles of sawdust from the activities of wood-boring beetles.

sawdust on wood pile

Sawdust on the hickory wood pile (click photos to enlarge)

I have often encountered the grubs of beetles while splitting wood, but I soon realized this was an exceptional concentration of these guys in this pile.

Hickory borer beetle larval chamber

A split log reveals the source of the sawdust – galleries from the chewing of wood-boring beetle larvae.

Hickory borer beetle grubs

The excavators – the fathead grubs of a long-horned beetle were falling out as I split the hickory logs.

As I was chopping this wood, I had a whole new respect for the chewing abilities of these larvae. I mean, hickory has a well-deserved reputation as a very hard hardwood (hence its common use for tool handles, etc.), and on several swings of the maul it seemed like I was trying to split petrified wood. And yet these 1/2 to 3/4 inch grubs had tunneled through it like it was cream cheese.

Hickory borer beetle pupal chamber

Pupa of a long-horned beetle in a chamber in the wood.

Hickory borer beetle pupae

Several long-horned beetle pupae that were exposed as I split wood.

This species of long-horned beetle emerges in early spring, so these pupae are almost ready. After mating, a female will lay up to 50 eggs (that explains the abundance in my logs) in the bark of weakened wood or wood that has been dead for no more than a year. Hatched larvae chew into the wood and feed for 10-12 weeks before making a larger chamber for pupating, where they will remain until the following spring.

Hickory borer beetle

One beetle started slowly crawling after it dropped out of a split log (I don’t think it was quite ready to be out in the world). It is a Hickory Borer (aka Painted Hickory Borer), Megacyllene caryae. This species closely resembles the Locust Borer Beetle, and both are considered wasp mimics due to their appearance (but they are harmless).

firewood

The freshly cut and split firewood. The dark spots visible on some log ends are the long-horned beetle galleries.

I admit to feeling a little guilty about dislodging all these beetle larvae and pupae but I think the Carolina wrens are quite happy about my wood chopping endeavors. But, I think there will be plenty of survivors in the remaining stack of logs to continue their boring behavior this spring. Seeing this community of critters in the wood and then feeling the warmth of the fire from these logs serves as a vivid reminder of the lasting legacy of a single tree. I look out the window and see so many stories in the forest…

4 thoughts on “How Much Wood Could a Wood Beetle Chew, If…

  1. Another interesting look into what we may see but often don’t understand, Mike. But I especially love that quote from Antoine de Saint-Exupery. Our trees are such magnificent creatures!

  2. Your posts are so interesting- please keep them coming. I share them with many others, you’re educating so many people! Love all your posts!

    On Wed, Mar 18, 2020 at 6:05 AM Roads End Naturalist wrote:

    > roadsendnaturalist posted: “The tree is more than first a seed, then a > stem, then a living trunk, and then dead timber. The tree is a slow, > enduring force straining to win the sky. ~Antoine de Saint-Exupery Last > week I cut and split some firewood from a hickory that fell across th” >

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