To my horror a large section of my garden and nearby lawn has an infestation of Japanese beetles, on leaves, on stems, on root areas and in the soil. The soil is clay like – in the Beach/Scarborough area and it’s the south side and sunny.
Greatly appreciate any help! Thank you.
Thank you for contacting Toronto Master Gardeners about this destructive invasive species, the Japanese Beetle. These pests will feed on about 300 species of plants.
Japanese beetles love hot dry weather. They lay their eggs in the soil under grass lawns. The larvae will overwinter in the soil and continue feeding as the weather warms in the spring. Once the larvae are full grown, they will pupate and emerge as adults in late June and early July. The winged adult beetles will continue to feed on foliage through July and part of August. Adult beetles emit a pheromone that helps them find each other.
Many say that the best method for control is to hand pick the adult beetles in the early morning, or late evening when they are less likely to be flying, and simply knock them into a container of soapy water, where they will drown. Begin this process when the adults emerge in late June and early July, and continue until early August.
You can also try to control this pest at the larval, or grub, stage using nematodes, a type of roundworm that feeds on grubs. Take care to select a type of nematode specific to the larvae of Japanese beetles, and apply as per manufacturer’s instructions. Nematodes are best applied in August, and watered into the affected area.
There are also pheromone traps available that will attract adult beetles. However, these traps may in fact attract more Japanese beetles to your yard from surrounding areas. The traps are most effective in large yards where the beetles can be directed to a location far away from your plants.
Toronto Master Gardeners receives many questions on the control of Japanese beetles. Please enter ‘Japanese beetle’ into the Search Box on the main page of our website. You will find numerous entries on this very topic.
Good Luck !