Japanese beetle (Popillia japonica) is an invasive species of Scarab beetle from Japan that first arrived in Nova Scotia in the 1930s. The adult beetles are "generalists," in the sense that they will consume the leaves of any ornamental, native or agricultural plants they can find.
The reason this species is considered invasive is that it has no natural predators in the region, and so it is able to spread uncontrollably. Higher temperatures during winter months also prevent larvae from dying back, while turf lawns provide the perfect food for new broods to develop.
Treating beetle infestations
There is no known treatment that has been proven to successfully eliminate the beetles from a community, but there are actions that we can take to reduce their numbers on public and private property.
As a small-scale trial, the municipality is using peppermint essential oil to deter the beetles from spreading on public property. The results should be clear by the end of summer 2025.
There are also plans to test the use of traps and lures in municipal parks in 2026.
Traps and lures
Residents can acquire traps and lures to manage beetles on their property. Be careful when using traps as a management strategy. Traps use chemical scents to attract beetles and can catch thousands of individuals in a week, but can also draw beetles from neighbouring properties. As such, traps work best when your neighbours use them too. It is a good idea to work together with other people in your neighbourhood to reduce the local beetle population.
Because around a quarter of the insects usually survive to feed on surrounding plants, place traps far away from the gardens and plants you want to protect from the beetles.
Japanese beetles feed on knotweed and multi-flora rose, making them a perfect place to hang traps.
Note: traps are at their most effective when used in combination with other management strategies, especially ones that stop the larvae from growing, like nematodes.
Nematodes
Nematodes are worm-like microbes that eat Japanese beetle larvae and that, when successfully applied, can reduce the amount of larvae living in the soil by more than 90%. Nematodes are safe to use and available commercially under various brand names.
Tips for applying nematodes:
- look for products used for “white grub” control
- apply either early in the morning, late in the evening or on an overcast day
- water for two weeks after application
- repeat annually, ideally in the spring
Milky spore powder
Another natural way to manage Japanese beetles is through the application of milky spore powder. Milky spore is a bacteria that builds up in the soil after the first two to four years of being applied. Like nematodes, the bacteria naturally infects and kills Japanese beetles.
Feed the birds
Birds are known to eat Japanese beetles, so an easy way to limit the population of beetles on your property is to encourage birds to flock there by introducing feeders and bird baths. Chickens are also known to be predators of beetles and may be a helpful way to reduce beetle and grub populations. (Before acquiring hens, however, please review the requirements stated in your local land-use by-law.)
Naturalize your lawn
Lawn naturalization is an effective long-term solution for reducing the number of beetles on your property. Since larvae thrive on the roots of turf grasses, uprooting your turf and planting native perennials instead will create a pollinator lawn that larvae don't like.
Disposal
To make sure that both trapped beetles and lures do not get into the municipality's composting system, dispose of the beetles in a regular garbage bag.
Please call 311 ahead of your regular garbage collection day to let collectors know that an invasive species will be contained in your trash.
