Eastern Michigan Hosta Society: First informational entry for EMHS Questions and Tips

From: https://www.aphis.usda.gov/aphis/resources/pests-diseases/asian-longhorned-beetle

United States Department of Agriculture
Animal and Plant Health Inspection Service

Asian Longhorned Beetle - About

Last Modified: Jan 22, 2016

About the beetle

The Asian longhorned beetle, or ALB, is an invasive insect that feeds on a wide variety of trees in the United States, eventually killing them. The beetle is native to China and the Korean Peninsula and is in the wood-boring beetle family Cerambycidae. Adult beetles are large, distinctive-looking insects measuring 1 to 1.5 inches in length with long antennae. Their bodies are black with small white spots, and their antennae are banded in black and white. Checking your trees regularly for this insect and looking for the damage it causes and reporting any sightings can help prevent the spread of the beetle.

ALB lifecycle and how it affects trees

Adult females chew depressions into the bark of various hardwood tree species. They lay an egg—about the size of a rice grain—under the bark at each site. (Females can lay up to 90 eggs in their lifetime.) Within 2 weeks, the egg hatches, and the white larva bores into the tree, feeding on the living tissue that carries nutrients and the layer responsible for new growth under the bark. After several weeks, the larva tunnels into the woody tree tissue, where it continues to feed and develop over the winter. Larvae molt and can go through as many as 13 growth phases. As the larvae feed, they form tunnels or galleries in tree trunks and branches. Sawdust-like material, called frass, from the insect’s burrowing can be found at the trunk and branch bases of infested trees.

Over the course of a year, beetle larvae develop into adults. The pupal stage lasts 13 to 24 days. After adult beetles emerge from the pupae, they chew their way out of the tree, leaving round exit holes approximately three-eighths of an inch in diameter. Once they have exited a tree, they feed on its leaves and bark for 10 to 14 days before mating and laying eggs.

Because ALB can overwinter in multiple life stages, adults emerge at different times. This results in their feeding, mating, and laying eggs throughout the summer and fall. While adult beetle activity is most obvious during the summer and early fall, adults have been seen from April to December. Adult beetles can fly for 400 yards or more to search for a host tree or mate. However, they usually remain on the tree from which they emerged, resulting in infestation by future generations.

Signs of ALB start to show about 3 to 4 years after infestation, with tree death occurring in 10 to 15 years depending on the tree’s overall health and site conditions. Infested trees do not recover, nor do they regenerate. Foresters have observed ALB-related tree deaths in every affected state.

Host Trees

Collectively, the tree species the insect favors are called ALB host trees. In the United States, known ALB host trees include all species of the following 12 genera:

Ash (Fraxinus)

Birch (Betula)

Elm (Ulmus)

Golden raintree (Koelreuteria)

London planetree/sycamore (Platanus)

Maple (Acer)

Horsechestnut/buckeye (Aesculus)

Katsura (Cercidiphyllum)

Mimosa (Albizia)

Mountain ash (Sorbus)

Poplar (Populus)

Willow (Salix)

Look for Signs of Damage

Besides seeing the beetle itself, there are distinctive signs that can be found on a tree that may mean your tree is infested, and if you see a beetle or suspect that tree damage is caused by the ALB, please report it by calling the hotline at 1-866-702-9938 or filling out the online Report It form:

Exit holes – In the warmer months the adult beetles chew their way out of the tree leaving, ¼ inch or larger, perfectly round exit holes.
Egg sites – Adult female beetles chew up to 90 oval depressions, called oviposition sites or egg sites, into the bark of the host tree. She lays a single egg beneath the bark at each site. These look like little wounds on the tree, and you can sometimes see the chew marks on the edges.
Frass – As the larvae tunnel and feed, it often pushes sawdust-like material or excrement, called frass out onto the ground around the tree or onto the tree branches.
Tunneling – After the egg hatches, the larva tunnels into the growing layers (phloem and cambium) of the tree and eventually into the woody tree tissue (xylem). If you have a fallen branch or are cutting wood, you may see this tunneling.

Other Signs of Damage

Weeping sap – Tree sap may be seen flowing from the wounds or egg sites.
Unseasonable yellowing leaves – Seeing leaves turning colors sooner than they should could indicate the tree is under stress.
Branches dropping or dying – If the tree has lost a branch or has a dead branch showing it could be a sign that something is wrong.

From
https://www.uvm.edu/albeetle/awareness/alb-and-host-trees-09-12-2012-print.pdf

United States Department of Agriculture

Forest Service Northeastern Area State and Private Forestry

NA–PR–05–12

September 2012

Asian Longhorned Beetle
and its Host Trees

Bruce L. Parker and Margaret Skinner Entomology Research Laboratory University of Vermont Burlington, Vermont

Kevin Dodds and Michael Bohne U.S. Forest Service Forest Health Protection Durham, New Hampshire

photo: Dennis Haugen, U.S. Forest Service
Closeup of oviposition pits showing mandible marks on the margin of the pits.

photo: Michael Bohne
Heavily attacked trees showing fresh and old oviposition pits on Sugar Maple.