Red Turpentine Beetle

2008 June 14

This one smacked me in the back of the neck while I was working in the yard the weekend of May 24, and got tangled up in the hair on my upper back until I grabbed it and pulled it out.

Red Turpentine Beetle

I then noticed there were several others flying about, so they are obviously something really common. It looks exactly like a Red Turpentine Beetle, Dendroctonus valens. This is a pretty likely identification, because (a) they are well-known pests of pine trees, (b) there is a pine plantation just behind our house, and (c) they emerge as adult beetles very early in the spring.

These are pretty robust little beetles, built like tiny tanks. They tolerate cold, and can push other beetles around pretty easily[1].


Unfortunately, it wouldn’t stay still for an extended depth of field shot, so here’s another where the legs and antennae are in better focus.


They have a pretty deep body, they are almost cylindrical in shape, which I expect gives them more room for musculature to do what they are evolved to do: bore under tree bark. Their eyes aren’t all that prominent, for the obvious reason that they probably don’t need them all that much.


They do have pretty aggressive mandibles, though. Here it is trying to gnaw a hole in my finger (it didn’t succeed):


It also flashed its wings at me a couple of times. The flight wings are these long, membranous affairs with a hinge in the middle, so that they can fold up neatly under the wing covers to avoid damage[2]. It was a lot quicker on the wing stowage than most beetles, it could go from wings fully deployed to wings completely tucked away in about 3 seconds, which is why we have to settle for a somewhat blurry picture of it here.


This is another case where we see that pest species get a lot more attention than species that are just kind of around. Since red turpentine beetles can kill pine trees, and pine trees are an important crop, a search on the name turns up a lot of Federal and State forest service sites talking about them. It turns out that, even though they are common and widespread in North America, they are considered a minor pest[3] because they rarely build up to epidemic numbers, and usually only kill trees that have been weakened by other causes.

Their life cycle goes like this: In the spring, adult beetles chew out a “gallery” underneath the bark of a pine tree, where they lay eggs in the living part of the wood[4]. The eggs hatch out, and the legless larvae burrow under the bark[5], growing for up to two years (in cold climates), or sometimes having two or three generations in a single year (in warmer climates). They overwinter as pupae under the bark, and the adults hatch out in the spring.

Red turpentine beetles are mainly a problem if trees are damaged by fire, or get injuries from logging equipment when a pine plantation is being thinned, or if living branches are pruned off of the tree[6]. The beetles can enter through undamaged bark, but most healthy North American pines can exude enough pitch and resin into the beetle galleries that they can prevent eggs from being laid and hatching[7]. A sick tree, or a tree with bark damage, can’t produce enough resin to protect itself, and so the beetles are able to get in and seriously damage or kill the tree.

So, these beetles probably aren’t causing any major damage to the local trees, but they are certainly here, and they are something to watch out for. The main defense against them evidently is just to keep your trees healthy, unwounded, and unstressed. Pesticides don’t work all that well, because the beetles and larvae spend almost all their time under the bark, where sprays won’t get at them.

[1] See, we’d been catching various types of beetles and putting them together in a jar in the refrigerator until I had time to photograph them all. So, I had dumped this one into a dish with two other beetles, thinking that they’d generally lie still. The other two were pretty stunned by the cold and mainly just lay there, but the red turpentine beetle kept marching around the dish, bulldozing them out of the way whenever it came across them. For its size, it’s a pretty unstoppable little beast.

[2] The basic insect body plan has 6 legs and 4 wings. Most insects that fly use all four wings for flying, but the beetles have modified their first pair of wings into protective covers for the rear wings, which they actually use to fly. This is one of the reasons why beetles are so successful: they get the advantages of having wings available when they need to travel long distances in a hurry, but they can also get into the rough-and-tumble of life without risking damage to their wings, or even having their wings get in the way. This makes them way more durable than other winged insects.

[3] Of course, if they get outside of North America, it’s another story. They are an invasive pest of pine trees in China, where the local species of pine trees have never built up any significant resistance to them. They’ve evidently been fairly devastating to Chinese pines in Shanxi Province and adjacent provinces since about 1999. We constantly hear about invasive species from Asia causing problems on other continents, but this just goes to show that the problem can go both ways.

[4] Even though trees are pretty large, most of the volume of a mature tree is dead. The only part of a tree trunk that is actually alive is the thin layer between the bark and the woody core. This thin layer is the only way for nutrients to travel between the roots and the leaves. If it is damaged in a large enough portion of the trunk to the point that it can no longer transport nutrients, then part or all of the tree above the damage gets starved for nutrients and dies. And, of course, bark beetles eat this part of the tree, because it is the most nutritious part of the whole plant.

[5] Woodpeckers love bark beetle larvae, this is one of the main things they are after when they go drilling away on trees. So, if you see a woodpecker pecking away at a tree trunk, it is a pretty good bet that the tree is already in a bad way and likely to die from something like a beetle infestation. By this time, the damage to the tree by the woodpecker is almost beside the point.

[6] This is probably one of the reasons why it is very rare to see pine plantations where the trees are pruned, even though pruning the trees would in principle make them grow straighter, reduce the number of knots, and in general make them much more valuable as lumber. If the pruning operation leaves the trees vulnerable to bark beetles like this one, then pruning could lead to unacceptable losses of the trees if the plantation is in an area where the beetles are present.

[7] If you look at pine trees, you’ll often see these yellow, sticky pitch blobs on the trunk. These are the tree’s response to bark damage. If the pitch is from a wound made by these beetles or other beetles like them, the pitch is mixed with “frass” (insect droppings and sawdust).

4 Responses
  1. June 23, 2008


  2. LadyBug G permalink
    April 2, 2013

    Very Helpful. Thank you

  3. Kristy permalink
    October 14, 2015

    I think I might have been bit by one is that bad?

  4. October 15, 2015

    Kristy: Nope. They don’t have venom, all they can do is nip you a bit.

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