Would you like to help stop the spread of an insect that could harm Washington’s fruit trees, grapes, hops, and a wide range of ornamental and native trees? By simply reporting locations of tree-of-heaven in your neighborhood, you can help state agencies detect a potentially damaging insect early enough to stop it from spreading into Washington.
The insect is called spotted lanternfly and state agencies are concerned about what it would do if it shows up. First detected in the United States in Pennsylvania in 2014, the spotted lanternfly and has spread to other states, including Delaware, Maryland, New Jersey, New York, and Virginia, despite federal and state quarantines and control activities. Dead spotted lanternfly have been found in California and Oregon as hitchhikers on goods from the eastern United States, but no live insects have been found yet.
Spotted lanternfly feed on everything from apples and cherries to hops and grapes as well as many native and ornamental trees. However, its main host plant is tree-of-heaven, or Ailanthus altissima, an introduced tree species that is a Class C noxious weed in Washington due to its potential economic and ecological impacts. [See our previous blog post to find out more about the connections between the tree and fruit crops]
Because of the strong relationship between the tree and the insect, state agencies are seeking location information of tree-of-heaven throughout Washington to more effectively monitor for spotted lanternfly. Insects are notoriously difficult to stop once they are established in an area, especially the flying ones! The goal is to catch the spotted lanternfly early enough to prevent it from getting established.
You can help by looking for tree-of-heaven and spotted lanternfly in your community. Report sightings to the Washington Invasive Species Council through the Washington Invasives mobile app or the online reporting Web page. Include photos, size of the tree or trees, and approximately how large an area they cover.
According to Justin Bush, executive coordinator of the Washington Invasive Species Council, “While we know the trees are relatively widespread, we don’t know exactly where they are or how large the patches are. We hope the public can help us better understand the distribution of tree-of-heaven as quickly as possible because of its relation to the spotted lanternfly.”
How to recognize tree-of-heaven
Medium sized tree, up to 80 feet tall and 6 feet wide. Grows as a single tree or in large clones from root sprouts.
Leaves are divided into an odd number of long, narrow, pointed leaflets. There are 11-41 leaflets pinnately arranged like a feather. The edges of the leaflets are not toothed (entire), except for 1-2 large lobes at the base of some leaflets. The leaves are dark green on top, pale green underneath and have 1-2 large glands on the underside near the base.
When crushed, the leaves and stems have a strong, unpleasant odor. Stems can be easily broken to reveal a spongy brown pith inside the stem that resembles peanut butter.
Tree-of-heaven bark on older trees is rough and looks like the skin of a cantaloupe. Young stems are smooth with greenish or light brown bark and are attached alternately on the stem. The stems have large V or heart-shaped leaf scars where leaves break off.
Flowers on tree-heaven are small, greenish-yellow, and arranged in large clusters on the ends of the stems. Seeds are formed on a long, twisted wing or samara, with one seed in the center of each samara. The samaras often hang on the trees in large clusters through the winter, making identification possible in the off-season.
Tree of heaven can be confused with several other tree species
The trees most often confused with tree-of-heaven are black walnut (Juglans nigra) and sumac (Rhus spp.), both of which have similar leaves divided into many long, pointed leaflets. However, the leaflets on both sumac and black walnut have toothed edges, not smooth like tree-of-heaven. Also, black walnut produces large round fruits and sumac has upright clusters of red berry-like fruits.
Ash trees also have leaves divided into leaflets, but their leaves and branches are arranged opposite, in pairs, instead of alternating up the stem. Even if stems break off, you should be able to find a scar on the opposite side of the branch for every stem and leaf. Ash trees generally also have fewer leaflets than tree-of-heaven.
If you are in doubt, include photos with your report showing the leaf shape, branch arrangement, and any fruits or flowers. The bark is also helpful. And if you are brave, crush the leaf and give it a sniff. I’ve read that it smells like rancid peanut butter or popcorn, but I’ve never tried it myself.
How to recognize spotted lanternfly
Spotted lanternflies are about 1 inch long, with distinct black spots on light brown or gray wings. Their hind wings have a distinct red and black pattern. They are very distinctive and there are few similar flying insects. See photos and information on the USDA-APHIS website.
What to do if you have tree-of-heaven
While tree-of-heaven is considered an invasive species and legally classified as a Class C noxious weed, most county noxious weed control boards, including King County, currently are not requiring removal of tree-of-heaven due to its widespread distribution. Landowners seeking information on how to remove tree-of-heaven or seeking non-invasive alternatives for landscapes can contact the Washington Invasive Species Council or join the November 1 Webinar.