Japanese beetle and Gypsy Moth


I leave at Etobicoke, Royal York and Eglinton
Every year I get a lot of Japanese beetles and Gyspy Moth.
I need your help as I have a nearly 1 Acre lot


Japanese beetles are a scourge in Ontario! The Halton Region Master Gardeners has an excellent and comprehensive post, What can I do about Japanese beetles?  in which they discuss the life cycle of the beetles as well as some of the plants that the beetles like the most (e.g., dahlia, hibiscus, hollyhock, rose) and other plants they don’t find attractive (e.g., poppies, columbine, coral bells, forget-me-not, foxglove, hosta, poppy).    When adding plants to your garden, consider those that the beetles find less attractive.

This post also reviews how to make your property less attractive to the beetles, including:  reducing the area covered in lawn (the beetle larvae love eating roots of some grasses), letting the lawn go dormant in July and August (to discourage the beetles from laying eggs), encouraging grass to grow quite tall – e.g., to 18 cm (7 inches – the beetles don’t like tall grass). The article provides lots more detailed information as well as links to additional resources.

It is important to know the life cycle of the beetles, so you can choose a method of getting rid of them.  The adult beetles emerge in late June to mid-July and the best way to control them is to go out in the morning and early evening when they are not moving quickly.  Knock them into a bucket of soapy water and they will drown.  Prevent or minimize an infestation the following year by killing the beetles in the larval stage, using nematodes, which will feed on the larvae.  The beetles lay eggs in July and grubs emerge a couple of weeks later, growing to full size by late September.  At this stage, they move to deeper areas under the surface, only coming to the surface the following spring, when they start feeding.  It is best to treat the soil with nematodes in late summer or early autumn, when the grubs are quite small and near the soil surface.   It is important to follow directions for how to apply nematodes, as they are quite sensitive to heat, moisture, sunlight and soil conditions.

Every 7-10 years there’s an increase in the gypsy moth population – the moth eggs are found on tree bark/trunks and  in mid to late April emerge as larvae (caterpillars), which climb into crowns of trees and eat the leaves.  Next is the pupal stage (June to mid-July) and finally the adult moth will emerge to lay eggs.   You can intervene at most stages of the insect’s life cycle to help control the infestation:

  • Scrape egg masses from trunks and branches until around now (it’s April 25) – often eggs are laid quite high up in the trees, so may be difficult to find. Drop them in a bucket of soapy water so they drown or dispose of them in a sealed container in the garbage.  Don’t just discard them on the ground, they could hatch.
  • During the early caterpillar stage, biological pesticides can be used (until mid-June at the latest – it’s only effective against the caterpillar stage). For example, a bacterium that is toxic to the young gypsy moth caterpillars is Bacillus thuringiensis kurstaki (Btk) – it is found naturally in the soil.  Contact your municipality to ask about their gypsy moth control program, which may include spraying in certain areas.  You could also consult a certified pest control expert if the area you need to treat is large.
  • To get rid of late stage caterpillars, wrap 45 cm (18 inch) wide burlap bands around tree trunks at around chest height. Use string and tie it around the centre of the burlap.    This will prevent the larvae from reaching higher areas of the trees as the critters will hide underneath the bands – check daily and remove them by hand and destroy them by dropping them in a bucket of soapy water so they drown.  Make sure you wear gloves as caterpillars are hairy and can cause allergic-type reactions.
  • The pupae (June to mid-July) can be removed by hand.
  • Don’t bother trying to get rid of the moths once they reach the adult stage in July to August – the insects are much more vulnerable during the other life stages.

Here are some additional resources:

  • Ask a Master Gardener. Japanese beetles
  • The Ontario Ministry of the Environment and Energy also provides an overview of the gypsy moth , the damage it causes and how you can help control it. Gypsy moth.
  • Ontario’s Invading Species Awareness Program has an excellent website, and you can download fact sheets from the site. As well, they encourage you to report gypsy moth sightings to the Invading Species Hotline.  See Gypsy moth .

I’d suggest contacting an arborist if you have a large outbreak of gypsy moths and they are damaging many of the trees on your acreage.  You can find an arborist in your area by searching on Landscape Ontario .

Good luck with keeping the trees and other plants on your acreage healthy this coming season!

April 25 2021