Help with insect pest identification


Hello. I live in Mississauga Lorne Park (QEW & Mississauga Road). My garden is alive and well with a pest this spring that is eating hosta, hydrangea and coral bell leaves. If you could help with identification (as per attached photo) and suggest a management strategy, I would most appreciate it! Garden is in shade for most of the day (gets morning sun) and our soil is sandy. With thanks.


The insect pest in your photo appears to be the adult black vine weevil, Otiorhynchus sulcatus, which feeds on a wide range of plants including Heuchera, Hosta and Hydrangea.  Adult female weevils feed exclusively at night and injury to leaves consists of notching or chewing at the leaf margins.

Understanding the life cycle of these insects is helpful, and some comprehensive and interesting information is available here:  Please keep in mind when you are looking at U.S. resources that Ontario’s chemical pesticide regulations are often different and much stricter.

You are seeing adult females (there are no males!) at this time of year. Although damage to leaves is unsightly, it is rarely serious enough to kill the plant.  There are a couple of strategies for managing this insect pest.  A previous Toronto Master Gardeners post provides some useful information on controlling black vine weevils at both the larval and the adult stages of life, and suggests optimal timing:   Nematodes, used as a soil drench at the larval stage as mentioned in this post, are available online and can also be purchased at most big box home and garden stores as well as hardware stores – look for products that reference grubs and nematodes, and follow the directions for application.