If you have boxwoods in your landscape, please take some time and read this article as it may prove useful to protect or treat your boxwoods. Scroll down to the end of the page if you wish to hire our services for consultation and treatment application.
What Is the Boxwood Moth and What is Happening in the GTA? The Box Tree Moth, Cydalima perspectails, or Boxwood Moth as it is commonly referred to in the gardening community, is a species of the Crambidae moth family native to eastern Asia. The species feeds on the leaves and shoots of Buxus (Boxwood Tree/Shrub) species, leaving the shrubs stripped of their leaves, with the hardest part of the plant structure intact (stems). Signs to look for in your boxwoods are the presence of frass (insect excrement) and a web constructed by the larvae and pupae in their development stages. General observations, which have not been confirmed by scientific studies, indicate that the species has a life cycle of approximately 45 days; 5-7 days as an egg; 10-15 days as larvae; 10-15 days as pupae; and 10 - 14 days as an adult. In a season, it is approximated that there could be between 3 - 4 life cycles or non-overlapping generations. The period of time in which these insects can survive the GTA weather may start as early as the end of March, and continue through mid-October or mid-November depending on weather conditions. At the end of the season, the larvae hibernate by enclosing themselves inside of the leaves of the shrub and the web. These leaves drop under the plant structure and/or canopy and are protected from the freezing cold by leaf-cover and the comparatively warm ground. The alterations to the life cycle of the species in Canada are still are unknowns as official studies have not been completed or presented to the public. The above information has been summarized by GreenTerrart based literature research and field observations up to this date.
In Depth Info About the Species This insect was detected in the late 2000s through parts of Europe. On November 2018, the Canadian Food Inspection Agency (CFIA) confirmed the presence of this pest on the western areas of the Greater Toronto Area(More specifically in Etobicoke as a suspected epicenter for the pest- most likely through Pearson Airport). Only until early 2019, nurseries, garden centres, distributors, the City of Toronto and Landscape Ontario became unanimously aware of the moth. These organizations, as well as CFIA, have been trying to study the species to generate better solutions to the continuously growing issue. Due to the lack of natural predators such as microscopic wasps and some introduced predators like the Asian hornet (Vespa velutina), the boxwood moth has been able to expand its range beyond its focal point in Etobicoke towards neighboring communities. The efforts to determine the extent of the pest are on-going. Public and private sectors are working together to map and keep the pest under control. Boxwood shrubs are among the most common used plant in landscape and gardens in Ontario due to their appearance and relative easy maintenance. It is estimated that approximately 1 in 5 urban landscape contain boxwoods in their design. These extensive use for boxwoods present an issue to control the pest as it has plenty of food source and it is difficult to track its movement.
What Should I Do as a Homeowner/Business that has Boxwoods? As a homeowner, you have three courses of action to consider if this is a problem in your property as well as your neighborhood:
Report, Prevent and Treat!
Let’s start with REPORTING. As with any other new invasive species, it is crucial for homeowners/businesses to report these types of pests. These pests should be reported to governmental institutions and experts in the industry such as the CFIA, Landscape Ontario, Garden Centres, and experts like ourselves. We are all collaborating to map the extent of this pest to come out with best practices and solutions as to how to control it, and hopefully eradicate it. So contact any of the above in case you get a glance of these insects in your house or neighborhood. The moth is very efficient at expanding its range, causing severe damage as previously seen in parts of England. The sooner you report it, the better it is for your neighborhood to be on the lookout.
PREVENT. If you or your neighbors suspect the presence of this species, start treating the boxwood with Bacillus thuringiensis (Commercially known as BTK). BTK is a widely used bacterium-based organic pesticide. It consists of a liquid medium harboring bacteria that gets into the digestive system of the larvae as these feed on the leaves of the shrub. The bacteria produce toxins that damage the gut of the host, culminating in paralysis and death. The application of this before the pest arrives in your neighborhood will enhance the chances of limiting the pest and protecting your shrubs.
Last but not least, TREAT! If your boxwoods are the unfortunate hosts of the pest is time to get serious about applying BTK. Based on our observations and the knowledge that has been gathered by others, BTK should be applied every 2 or 3 weeks depending on the degree of infestation. In some cases, the infestation may be too advanced, and at this point, it may be better to cut your loses and replace the shrubs. Additionally, a fall clean up must be completed in order to get rid of the remaining pupae that may be lurking underneath the leaf-cover. The appropriate application of treatment in conjunction with the cleaning of the area may increase the chances of your plants surviving. Again, professionals are still testing solutions for more effective alternatives, but this is the best advice we can give you at this time. We’ll continue monitoring the behavior of the species, and keep you informed of any new information that is shared in the industry.
How can GreenTerrart help you? Taking action early and completing the appropriate steps described above is essential to attempt saving or preventing the loss of more boxwoods. GreenTerrart is continuously monitoring the areas of operation and the effectivity of the available treatments in the market. We have come up with a treatment package starting at $80/application for first-time clients and starting at $60/application for regular clients, depending on the size, existing contract, and quantity of boxwoods in the property. The average application goes between $60 and $300 per application. The package includes on-going seasonal monitoring of infestation, treatment applications, professional consultation, and materials of application. Finally, as with any other treatment, the effectiveness of these products is not a guaranteed solution. This is a biological non-toxic treatment, which requires correct application, consistency, and care for it to work at its best. The sooner the pest is caught and dealt with, the better your chances. New treatments are continually being developed that may prove to be better. Our best advice for you is to keep vigilant and take action as soon as possible if you detect this issue. The application of the BTK is safe since it is an organic pesticide. We advise you that if you decide to do it on your own, read the product instructions and directions, and understand the appropriate methodology of the application. To see what the moth does to your boxwoods, click on the following link for a YouTube video:
How to Identify if You Have Boxwood Moths in Your Property? The gallery below provides you with examples of the moth at different stages in its life cycle (larva, cocoon, and adult). Please examine carefully your boxwood trees and shrubs and try to identify them. Once identify contact Landscape Ontario or GreenTerrart. Landscape Ontario will only records your report, but they won't come out to your house. Landscape Ontario is asking this from residences in order to track the pest and generate a more effective way of control. GreenTerrart will come out , document the finding, and apply the necessary pest control under a formulated schedule. The application must be done at least three times throughout the year. Application does not guarantee the survival of the plants. Depending on the degree on infection your shrubs may or not be salvageable. We have also provided examples of affected trees/shrubs below. Look for these signs of infection:
Bitten leaves. The stem is intact and not eaten.
Black balls less than a 0.2-1mm in diameter (frass a.k.a. excrement). Mostly in clusters.
Curled inward leaves.
Webbing within the branches. The webbing is tightly packed and/or dense.
Presence of larvae or "worm". The larva are green "worms" with black and slightly less visible white dots that run along the length of the larva. These may be between 1cm-3cm in length
Presence of adults. The adult a.k.a. Imago is white with a black/brown border around the entirety of its body when the wing as extended. These adults don't stay in the air. Moths tend to skip fly, rather than glide like butterflies do.
From a distance the trees/shrubs look brown or as if they were burnt.
UPDATE: Observations after treatment application:
5-10% foliage reduction compared to 30-40% foliage reduction on boxwood without the treatment
The moth population has continued its normal development at a steady pace within the areas of the GTA where it was originally spotted by our team.
The optimum conditions of applying BTK is early mornings or late afternoons when temperatures are at least under 18 Celsius.
These observations are simply what our team has noted throughout the season. Further studies on the species should be conducted in order to determine the actual effectiveness of the treatment and its optimum conditions.
What do you have to do after application?
Cleaning your yard thoroughly, especially areas where the boxwood shrubs reside. A thorough fall clean-up of the yard will reduce the overall chance of dormant moth generations to come back next year. By clearing out debris that accumulate throughout the season on flowers, one takes off a layer of suitable habitat in which the moth species may be lurking until next year.
Additionally, subsequent applications of BTK should be part of the cleaning duties so that any of the remaining pests are kept in control as individuals start to die off due to the colder weather. Once the winter is gone, additional BTK applications should be applied in order to keep the pest at bay.
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