Are grubs destroying your lawn?

Many people are discovering that grubs, the larvae of some beetles, can destroy your lawn if not detected early and treated.

Although the most common destructive grub in Canada was originally from the native June bug, recent introductions of the Japanese beetle and the European chafer within the Niagara region have resulted in their migration further east and north in Ontario, causing havoc to lawns in eastern Ontario.

Adult June bugs are a shiny red-brown color, reaching up to 1 inch in length.  The Japanese beetle is much smaller, less than 1/2 inch long, with a metallic bronze and green color.  An adult European chafer is similar in size to the Japanese beetle, but tan or light brown in color.

All of these grubs have c-shaped bodies and six legs, however, the June bug larvae are white, while the larvae of the Japanese beetle and European chafer are a beige color. Upon hatching the grubs are tiny but reach a mature size of up to 1.5 inches.




Another major difference between the types of grubs is that the June bugs take 3 years to mature while the Japanese beetle and European chafer only take one year.  As a result, infestations of white grubs (June bugs larvae) happen every third year, while infestations of the other two types can happen annually.


chafer life cycle


Although grubs prefer the fibrous roots of your lawn the best, they do feed on other plants, especially carrots and potatoes.  Ryegrasses and fescues tend to be more resistant to grubs in your lawn, while geraniums and larkspur are immune to grubs in your gardens.

So, how do you know if your lawn is being attacked from below by grubs?  These are a few signs:

  • patches of lawn turn brown and can easily be lifted in chunks
  • skunks and birds, mainly starlings and blackbirds, will tear up chunks of lawn to get to the grubs
  • patches of affected lawn often feel spongy and soft to walk on


The best ways to prevent grubs are:

  • keep your lawn healthy as adult beetles prefer weak, stressed lawns for laying their eggs
  • aerate and remove excessive thatch annually to break up compacted soil and ensure good drainage
  • do not cut your lawn too short as adult beetles prefer short, dry lawns to lay their eggs
  • leave lawn clippings on the lawn and use fertilizers with high potassium and nitrogen
  • water your lawn deeply but infrequently to encourage deep roots and promote drought tolerant lawns
  • hand pick adult beetles putting them in soapy water to kill them
  • attract natural predators like blackbirds and starlings with birdhouses
  • use a mixture of ryegrass and fescues lawn seeds


To treat grub infestations:

  • apply nematodes (microscopic, parasitic organisms) to attack the grubs. Be sure to read package instructions on when and how to apply them
  • water your lawn heavily to bring them to the surface so birds can eat them
  • apply composted manure and grass seed to replace the destroyed lawn patches


Hopefully, you will not experience the damage these grubs can do!  If you do, I hope these tips help get rid of them quickly.


How and when to water your garden and lawn

In drought conditions like we have been experiencing here in the Ottawa (and most of Ontario) area, it is important that you know how and when to water your garden and lawns if you feel you must do so.

  • water plants in your garden at ground level, at the base of the plants.  Don’t spray the leaves of plants.  The hot sun will burn the wet foliage. (see pictures below)
  • water early in the morning or just before sunset so the water does not evaporate as quickly as it leaves your hose.
  • water well less frequently.  A long soak every few days is much better than a quick daily spray.  This encourages deep roots for your plants (and lawns too)
  • don’t forget to water your trees too.  Let water drip from a hose at the base of the tree for an hour when no rainfall is received for 4 or 5 hot days.
  • remember, lawns will recover, but many plants and trees will not