curled leaves of tree with small holes in trunk

Question: hello, we planted this tree 2 years ago. About 1 month ago (June) we noticed that the leaves were changing but thought it was part of the normal life cycle. Now (July) you can see in the pictures that the leaves are curled and seemingly dried. We also observed some wood dust collected on a branch and on the mulch and also some small pin-sized holes in the trunk. We have not seen any insects though the signs may be apparent. Is the tree completely dead? Based on your diagnosis, could we treat at this point? Please let us know. thanks.

responder: The Question Asker Replied July 25, 2023, 12:58 PM EDT
response: Upon further inspection of the picture I saw a shiny bit on the hole. All the insects (beetles?) appear to have their rears facing outside and level with the bark surface of the tree. Upon poking their rear they crawl inwards. Separately, can you comment on this biological phenomenon where all the insects prefer to rest on the surface of the tree in this orientation? thanks

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied July 26, 2023, 1:45 PM EDT
response: We see indications in the photos of what appears to be Ambrosia Beetle, a fairly common beetle group (some species are native, some not) that can kill trees as they bore into trunk wood. Their tunneling itself does some damage, but more importantly, it's the fungus they introduce in the process that they require for consumption which causes more tissue damage in the trunk, and neither the fungus nor the insects are directly treatable with a pesticide. Some trunk applications might discourage or prevent adult beetles from starting new infestations in a tree, but once the insects are inside, they are beyond treatment. The sawdust and beetle bodies visible in the holes are their activity of pushing-out bored wood as they expand a tunnel.  Trees under stress are generally those attracting these beetles, even if that stress isn't causing obvious symptoms yet like wilting or leaf shed. The pictured tree looks like a Red Maple (Acer rubrum). Red Maple trees thrive in soils that remain consistently moist, though they can tolerate some root wetness better than drought. It's hard to say when the stress for this tree began, or which exact stressor contributed to susceptibility to borer attack, but it might have occurred a year or two ago, or at least a few months ago this year; we have had quite a dry growing season overall so far in most of the state.  Given the extent of the damage, we do not expect the tree to recover, so it can be replaced. The trunk injury near a branch junction shown in one of the smaller photos may be a canker, which can be caused by fungi or bacteria, and it has killed some sapwood which can prevent the canopy from receiving enough moisture and nutrients from the roots. It cannot be treated, and some canker-causing pathogens similarly take advantage of trees under stress from drought, injury, or other causes.  If you replant, you can use the information on our Planting a Tree or Shrub and Watering Trees and Shrubs pages to make sure a new tree gets off to a good start to establish well. Of particular importance is planting depth (too often, trees are inadvertently planted too deeply) and mulching well (but not too deeply) around the trunk base to keep the lawn far enough away from the tree, along with regular monitoring for watering needs for the first full year or two after planting.  Miri