As Yard Thaws, Get Ready To Battle Beetles

Mother Nature is really playing hardball this year. As if shattered, crippled trees were not enough, she may be planning to throw us a curve: insects. Because of the thousands of damaged pines and Douglas firs, we may be seeing major infestations of various bark beetles - mountain pine beetles, ips beetles, red turpentine beetles and fir engraver beetles.

All of these tiny insects have one thing in common - they are attracted to the distress calls of weak, stressed or injured trees. While moving in for the kill, they may also make targets of seemingly healthy pines and firs. Because their flight begins anytime from April on, we must work fast to clean our property of downed limbs, slash piles and topped trees.

Ips or engraver beetle: These tiny 1/8-inch, reddish-brown or black beetles usually attack immature pines and the tops of old pines. They bore into the inner bark, destroying the phloem, the part of the vascular system of the plant under the bark that is responsible for transporting nutrients.

The Ips beetle overwinters in duff - the soft, earthy matter found on the forest floor. As temperatures warm, these beetles begin awakening. By April, they take flight in search of weakened trees and fresh slash piles (piles of tree limbs). Here, they tunnel into the phloem and lay their eggs. Under the bark, the hatched larvae begin carving out galleries in the soft, moist tissue.

By June, the larvae have finished feeding. The little grubs pupate and become adults. The adult beetles emerge, lay eggs and a second generation is produced. The adults of this generation emerge in the fall and drop to the ground to overwinter.

Damage from the Ips beetle can be recognized by yellowing and browning needles, red sawdust in the cracks and crevices of the outer bark and forked galleries carved into the inner bark.

Mountain pine beetle: These are the real menaces. Though many of you may think of this beetle as a large fellow, the pine beetle is really only a little black villain, 1/4-inch long. As opposed to the Ips beetle that works on the top of the tree, this fellow works on the trunk of the tree.

An infestation of these critters can destroy an entire forest.

The mountain pine beetle enters trees in July and August and lays eggs under the bark on the main trunk. As with the Ips beetle, the eggs hatch into legless, white larvae which feed on the phloem of the tree. The pine beetle also carries a blue stain fungus that plugs the vascular system of the tree. The tree dehydrates and eventually dies.

The larvae of the mountain pine beetle overwinter in the tree, emerging in June and July the following year. They begin the search for weakened trees and start the process again. There is only one generation of mountain pine beetles a year.

Evidence of the beetles is small, perfectly formed, pinhead-shaped holes along the trunk. These are adult emergence holes.

Tubes of pitch or small piles of reddish sawdust found on the trunk are also excellent signs of beetle infestation.

Red turpentine beetle: This fellow feeds near the bottom of a tree, and usually on the weakest and largest specimens. These red-brown beetles are the larger of the three - a whole 3/8-inch long. The larvae feed from June to October, mining fan-shaped galleries that may extend below the soil line.

Fir engraver beetle: Though this culprit prefers white, grand and red fir, it will attack injured Douglas fir, subalpine fir, hemlock and Engelman spruce. It is a tiny (.02 inch), shiny black beetle with a sawed-off posterior.

We normally don’t detect pitch tubes with the fir engraver. Instead, we may see streams of sap flowing from the trunk.

The engraver may be selective on which part of the tree it kills. It may choose to kill only single branches by cutting off their water supply from the trunk, or it may go for the top of the tree, or in worst cases, the entire tree.

What can be done to protect our trees?

Once the beetles have entered the tree, there is nothing that can be done except to remove the tree. Obviously, the best offense is a good defense.

Remove all downed limbs and slash piles. Either chip them for mulch, burn if you can, or haul them to the incinerator.

If you leave the piles, cover them with plastic and secure the plastic to the ground. Either bury the loose ends or anchor them with stones, etc. We don’t want the beetle to get in or out.

Cut all topped pine trees to the ground and debark the logs or cover the logs with plastic as explained above. Try not to stack the logs in a wooded area.

Above all, give special care and attention to your remaining healthy trees.

Don’t pound nails into their trunks. Don’t hit them with lawnmowers or weed whackers, and don’t prune pine and fir during beetle flight. Remember, the beetles are attracted by the pitch smell.

And most important: Give them a slow, deep watering once a week.

There may be commercial value to your logs. The Spokane County Conservation District has a list of logging contractors who may be able to help with tree removal in rural areas.

If you have any questions about storm-damaged trees, please contact the conservation district office at 353-2120.

Let’s hope Mother Nature is sent to the showers for the rest of the season and that the infestations are less severe than we anticipate.

, DataTimes MEMO: Phyllis Stephens is a horticultural consultant and landscape designer in Spokane.

The following fields overflowed: CREDIT = Phyllis Stephens The Spokesman-Review