We are aware that some individuals have inquired about a specific invasive insect, the boxwood moth, which may be affecting their trees. We are always happy to receive these calls, which is why we want to tell you all about it, as well as recent developments, to show that it could be a problem. Our job is to prioritize tree healthcare before we ever consider removing them, and one of the main causes for this is tree diseases, many of which can be caused by insects like the boxwood moth.
In this blog, we are going to explain what the boxwood moth is, where it came from, what it does to affect trees, how to stop it, and more.
What is the Boxwood Moth?
The boxwood moth (Cydalima perspectalis), also known as the Box Tree Moth (BTM), is an invasive insect native to Asia. Its name is indicative of the very plants that it affects, as it primarily targets boxwood shrubs and boxwood trees.
They are an insect that can spread across many regions, as detailed by a report from Cornell in the last year, saying, “BTM first appeared in New York State in 2021, likely carried on a storm from a recent infestation just across the border in Ontario, Canada. Currently, a federal quarantine prevents export of boxwood nursery stock from counties with known infestations.”
This report notes that boxwood plants/trees are the primary food source for the moths, and given how common boxwood trees and boxwood plants are in Western New York and the regions around it, it’s important to make sure people who live around them know about the moth. Especially considering that most people probably wouldn’t consider moths to be an invasive species of insect that damages plant life. These are important details to know!
How Do Boxwood Moths Affect Trees?
Like almost all insects, the boxwood moth is usually present during the warmer weather months from late spring/start of summer in May to early fall in a month like October.
One of the best ways to detect a boxwood moth is actually by its first form, the caterpillar. Understanding where it begins is ultimately one of the best ways to understand how it affects plant life. Yes, moths like butterflies also begin with the caterpillar stage of their life cycle, and a boxwood moth’s caterpillar has a particular look to it, as you see below.
The larvae of a box moth feed on the leaves and bark of boxwood plants and trees. When they do this, they produce webbing and frass, which is just another way to say their excrement. The leaves start to brown, and defoliation also follows. These caterpillars are very good at hiding from you, but where you’re most likely to find them is hanging off the sides of leaves.
The important thing to note about the moths themselves, post-caterpillar stage of the life cycle, is that their presence alone will be enough for you to ask questions. The moth may not do much harm to the boxwoods, but their caterpillar counterpart will, and that should be enough for you to make inspections on your plants and trees.
You’ll be able to identify the moth through their white wings with brown borders, but sometimes you might also see it be entirely brown (see below).
The Proper Way to Treat The Boxwood Moth
In the case of what you should do to treat these invasive pests, biologically, there are still some questions left to be answered as far as how to treat them that way. Some biopesticides can be used against moth species and can help prevent boxwood from being infested by these pests. We don’t recommend just spraying any random pesticide because that could cause damage to the plants. Talk with a professional and read those labels! You should ALWAYS ask an arborist before using any chemicals.
From a non-biological perspective, the best way to handle this is by talking to those professionals, the certified arborists whose job it is to properly analyze if your tree is healthy or needs to be treated. Trimming and pruning affected branches with the diseased bark and leaves is your best option. If the disease and insect infestation are too much and cover the tree to the point where it’s dying too fast, then tree removal would be your last option.
All of these possible scenarios will be given a diagnosis by an arborist and it’s important that you notice this early on as best as you can so we can preserve the health of these plants. Give us a call when you can and we can’t wait to help!