Question
I live in the Thumb of Michigan, and have a pussy-willow tree that started the season by not much of it flowering(the little fuzzies), then only part of the tree got leaves(about 1/3), and then I noticed wood pulp on the leaves of the hostas that are planted underneath it. I didn't realize what was happening and about 2 weeks later I noticed that the leaves were wilting and drying and that there was more wood pulp underneath. I then started to really pay attention and within about a week the whole tree was brown and dying. I checked the trunk and there are many small holes in it. What is happening, what should/shouldn't I do, and is it too late? Could this be the Emerald Ash bore, there have been problems in my area because of them? I didn't see any insects on the tree except for rolly-polly bugs(?) and small ants. There aren't any ant hills around the base of the tree. Thank you for any information, I don't want this to happen to any of my other trees or to my neighbors.

Answer
I do not think it is emerald ash borer, but a borer on willow. A cryptic weevil as an adult, the damage from the poplar and willow borer, Cryptorhynchus lapathi, is all too obvious. This borer can infest in high numbers in preferred hosts causing high levels of mortality to a stand. Hosts include willow, poplar, alder, and birch. Willow is the preferred host, but hybrid poplar stands can suffer heavy losses. Solomon (1995) reports that balsam poplar and black cottonwood are susceptible while quaking aspen, alder, and birch are rarely attacked.

Both adults and larvae can overwinter in Canada and so are likely to do so in areas west of the Cascades. Summer into fall is the period when adult weevils emerge. The adults are most active in the evening and morning. These weevils can fly but do so rarely as they are sedentary. The newly emerged adults feed on bark of new stem shoots. They mate and can lay eggs shortly after emergence (2 to 10 days). Eggs are laid in crevices of the bark. Females can also chew into the bark, making round holes in which they oviposit one or several eggs and pack with bits of wet sawdust-like wood. There are two peak egg-laying periods: the first in March and April by overwintering adults; and later in July through October from the newly emerged adults (Solomon, 1995)(Garbutt and Harris, 1994). Adults can live two to three years (Garbutt and Harris, 1994). The adult weevils can make a stridulating sound when handled.

Larvae move from overwintering tunnels between the bark and wood, deeper into the stem often into the pith. Pupation occurs in frass plugged galleries, usually from mid-July through September and lasts two to three weeks.

Tree damage includes frass-plugged entrance holes; bark cracking and weeping; round exit holes (often sawdust at base of plant), galling of trunks, larval tunneling which girdles the trees, tree breakage, and secondary pathogens infecting borer wounds. Attacks are most common in stems 2.5 to 10.0 cm in diameter (Solomon, 1995). Galleries are round and often packed with frass.

The borers in the trunk can be treated with an insecticide called Merit or Onyx. This is sprayed on the trunk killing the insects under the bark. OR you can use a soil applied insecticide called Bayer Advanced Tree and Shrub Insect Control. This is applied to the soil around the tree and the roots will carry it to the stems killing the borers.