Monday, July 23, 2012

The Northeastern Pine Sawyer Beetle

From the afternoon into the early evening in mid to late summer, a silence often develops as the heat of the day peaks and then starts to cool; as birds cease to sing and amphibians lose their urge to call. In the stillness between periods when leaves rustle from light summer breezes, the sound of a grinding or twisting-scraping can be heard coming from a fallen softwood log or a dead standing evergreen.

This low volume creaking noise is particularly evident in downed white pine trunks that lie in open and semi-open settings. It is caused by the wood boring activity of the larvae of the Northeastern pine sawyer beetle (Monochamus notatus), a large, grotesque looking bug that is widespread across the Adirondacks.

The Northeastern pine sawyer is the largest species of long-horned beetle in our region; the adult may approach two inches in length. This is greater than other common types of similar beetles, like the white-spotted sawyer and the Asian long-horned beetle, which has become a serious pest to hardwood trees. Both of these other beetles average an inch to an inch and a quarter in length. Aside from its size, the adult Northeastern pine sawyer is also distinguished from other long-horned beetles by its drab gray color. Most other species are considerably darker and have other distinguishing markings on their back.
As is the case with other members of this group of insects, the pine sawyer beetle has an exceptionally long set of antennae. The noticeably jointed “feelers” of the male Northeastern pine sawyer can exceed 3 inches, which is almost twice its body length, and those of the female are similarly hard to overlook as they are close to the length of her body.

After mating, the female searches for a pine, spruce or fir tree that is dying or has recently fallen to the ground in which to place her eggs. Trees that grow near some type of open setting, such as along the shore of a lake, near the edge of a highway, golf course fairway, or power line are strongly preferred as the larvae that eventually hatch, quickly enter the wood and function better if their surroundings are warmed during the day by the sun. Pine trees that grow on steep, south-facing slopes are also used by the Northeastern pine sawyer since conditions inside their trunks become suitable as the sun regularly bakes them.

The oversized set of mandibles or jaws of the larva enables it to cut away small fragments of wood creating an opening into the fallen trunk that measures just over a quarter inch in diameter. By repeatedly shaving narrow fibers from the log directly in front of it, the large white grub is able to construct a tunnel several inches deep into the wood. Tiny, elongated stripes of wood are eliminated from the entrance and eventually fall to the ground forming a small, yet noticeable pile of woody debris that is evidence of its presence and recent activity. A single fallen pine tree in an open setting typically has numerous individuals residing within, as the female will lay many eggs when an ideal opportunity arises, which can be seen by the many small piles of woody residue below the log.

As it chews, the larva is able to extract nutrients from the layers of inner bark, the cambium and then the sapwood of various conifers. Because the trees into which it bores are either already dead, or are well along in the process of dying, the Northeastern pine sawyer is not considered to be a forest pest. However, for loggers that have left the trunks of numerous white pines in an open staging area for more than a month during summer, the wood boring actions of this beetle can reduce the value of any wood destined for a lumber mill.

Adult Northeastern pine sawyers are known to feed on the needles of various evergreens, however the relatively small amount of foliage which they consume apparently does not negatively impact the tree.

Because it resides within a protective wooden chamber, the larva has few natural enemies. Woodpeckers are occasionally willing to chisel out an individual that is still close to the surface of the trunk, however, the deeper the grub penetrates the wood, the less likely a woodpecker is to expend the energy needed to extract one of these bugs, despite its large size.

As summer begins to wane, fewer noises can be noticed, especially during the day. One sound that is unmistakable when heard is the soft, creaking-grind that comes from inside a pine log. This is the Northeastern pine sawyer which is chewing its way into a spot where it will pass the winter undisturbed here in the Adirondacks.

Photo courtesy University of Wisconsin-La Crosse.

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Tom Kalinowski

Tom Kalinowski is an avid outdoor enthusiast who taught field biology and ecology at Saranac Lake High School for 33 years. He has written numerous articles on natural history for Adirondack Life, The Conservationist, and Adirondack Explorer magazines and a weekly nature column for the Lake Placid News. In addition, Tom’s books, An Adirondack Almanac, and his most recent work entitled Adirondack Nature Notes, focuses on various events that occur among the region’s flora and fauna during very specific times of the calendar year. He also spends time photographing wildlife. Tom’s pictures have appeared in various publications across the New York State.

13 Responses

  1. David Gibson Dave Gibson says:

    Thanks, as always, Tom for a very interesting wildlife biography. You can hear these buggers still chewing on hundred year old Adirondack beams !

    • Bill Pittman says:

      Mr. Gibson, I don’t think you’d have pine sawyers chewing on such old beams in a house. Most of the long-horned beetles won’t infest or reinfest structural wood. I imagine that you’re hearing the chewing of something like the old-house borer, an unusual long-horned beetle that does infest structural beams, or maybe a furniture or death-watch beetle.


      • Ellen La Que says:

        You can also HEAR carpenter bees chewing wooden structures – but then you would also have occasion to see them buzzing about..but they do their chewing mostly in the evenings when temps are cooler.

        • Ellen La Que says:

          I came here today as my little girls and I were visited by a pine sawyer beetle on our deck this afternoon. We live right on a sunny strip of highway in NY flanked by large pine trees…”A place beyond the pines.” 😉 Very interesting info!

  2. Rachael says:

    Me and my husband got a log bed about 1 month ago and didn’t notice anything unusual, now we are finding big beeetle like bugs that I just found online that are known as Pine Sawyer Beetles found in dead or dying pine. I figure there was larvae in the wood and now they are maturing and coming out?? Will they go away do we need to get rid of our bed? I don’t know what to do I love our bed but I can’t not share it with bugs!

    • Tom Kalinowski Tom Kalinowski says:

      Hi Rachael: You can usually tell if Pine Sawyers beetles have invaded the wood, as their entrance hole is large enough to be noticeable. (About the size of an apple seed.) If there are only a few holes in the piece of pine, chances are that there may not be too many adults hatching out. If there are many holes in the wood, then you may want to have it treated by a pest exterminator, or leave it outside for several weeks until all of the adults exit the wood, and then bring it back inside. Just make sure that no additional adults place their eggs on the wood and have the developing larvae bore into the wood.
      Good Luck with this interesting problem!

      • Cindy Ehrlich says:

        We have a problem in San Francisco similar to Rachael’s. We bought four 6-inch diam stripped logs cut into 27″ legs for a big table. The wood, wrapped in clear-ish plastic, sat on our living room floor for three months or so. We began to be visited daily by one mature beetle after another, male and female. County ag has identified them as Pine Sawyers & ruled out Asian Longhorned. Meanwhile we taped up wrapping holes and put the package in our bathtub, where they have taken on additional arty holes about the diameter of a pencil. We found a couple of bores+sawdust in our lacquered fir floor where the bag had been. Montana sellers said it was impossible because the logs had been heat treated. Grrrrrrr

  3. chip says:

    Just found what appears to be an adult female on my garage wall here in Orrington, ME….Used your info to educate the kiddos on the fact it’s not a pest like our invading Asian Longhorn. Thanks for the info

  4. Allyson Hamlin says:

    Hello Tom,

    Your informative write up on this massive beetle has helped me identify our problem. My family has a lake house in Muskoka, Ontario. Last summer we had a fire on the property which affected approximately 15 trees. We have birch and pine trees that are 100 years old. This summer we noticed a low key creaking sound and when we investigated further we noticed numerous small circular holes that had been carved out in the damaged trees. At the base of the tree were mounds of sawdust looking stuff. I assumed it to be some sort of small termite or beetle. We did see this large grey beetle several times, but didn’t think it was the culprit. Now I have no doubt that the beetles attacking our trees are the Pine Sawyer Beetles. We have taken down about 7 trees, but left some to see if they can rebound. They are huge pines that still have green leaves. However, they have been taken over by these beetles. Is there a danger of leaving these trees up much longer and will the heathy trees be affected down the road. So far, no healthy trees
    have been affected. What should we do??

    Thank you!


  5. Michele says:

    Omg. It’s January 15, 2014 and one of these just crawled out of my bathroom sink drain! I live in Michigan and would be interested to know why it was in my drain. I’m a bit creeped out! Thank you for any answer!

    • Tom Kalinowski Tom Kalinowski says:

      Hi Michele: I would also be a bit creeped out if something like that crawled out of my drain. Without actually seeing the beetle, I can not say for certain if it was a Pine Sawyer beetle or some other type of bug, like a leaf-footed bug that happened to wander into the drain and simply crawled out when you were there. I have hear that sometimes pine sawyer beetles emerge from pieces of wood brought into the house in mid-winter, and are exposed to the warm air for several weeks. I occasionally get various bugs in my house during the winter which come in on pieces of firewood. I hope my response is helpful, and thanks for reading the Almanack.

  6. Jessica smith says:

    Are they harmful to people?

    • Tom Kalinowski Tom Kalinowski says:

      Hi Jessica:
      Like all beetles that occur in the Adirondacks, they are NOT harmful to humans.

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