What’s happening to the trees?
What’s happening to the trees?

What’s happening to the trees?

It’s an eerie site – trees that should be full and lush with summer growth still look like they’re waiting for spring to arrive. What’s going on?

It’s the spongy moth.

Spongy moths (previously referred to as gypsy moths) are European moths that are currently infesting much of the eastern and mid-Atlantic US. Just like The Very Hungry Caterpillar, they munch on foliage until trees look bare.

According to the USDA, these moths particularly like to eat

  • Aspen
  • Birch
  • Cedar
  • Cottonwood
  • Fruit trees
  • Larch
  • Oak   
  • Poplar
  • Willow

Signs of infestation include bare trees, clumps of fuzzy yellow egg masses, and visible caterpillars. At this time of year, you are most likely to see caterpillars. Be careful, as some individuals are prone to skin rashes from contact with the caterpillars.

What can you do?
Here’s what the New York State Department of Environmental Conservation recommends:

  • Squish and scrape: If you have just a few trees or a small number of moths present, squish them. Adults can be crushed, while eggs can be scraped off and dropped into a container with some detergent.
  • Band, barrier, and trap: In late April, sticky/barrier bands may be placed around the tree’s trunk to catch caterpillars when they hatch and crawl. If you choose to use a barrier band, please check it often in case unintended wildlife pass through, and replace as necessary after rain events. In mid-June when caterpillars are larger, replace sticky/barrier bands with a burlap trap. View detailed instructions on how to do this on the University of Wisconsin website.
  • You may also determine that chemical treatment is necessary. More detailed information is available on the DEC website linked above.

Will my trees die?

It depends. You may be able to help trees by weeding around the base, mulching, and watering regularly – they’re stressed out by the spongy moths and need a little extra TLC to recover from their trauma.

If a conifer tree (those with needles like hemlocks and firs) loses more than half its needles, it is more likely to die. Check the tree in late August/September after the caterpillars have disappeared to see if any new growth has started. If not, the tree is likely dead. Healthy deciduous trees (those with leaves like maples and oaks) may grow new leaves in July and August. This is a sign it will likely bounce back. If a tree loses all of its leaves and does not re-bud next spring, it is dead.

Caterpillar image courtesy University of Madison – Wisconsin.

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