Lawn Grubs

Grub out Lawn Grubs

Know Your Enemy


Lawn grubs can significantly damage your lawn, and you may not notice significant damage until infestation is well underway. 

Lawn grubs are generally white, and their bodies have a typical “C” shape to them. Grubs are larvae, and if left to mature, will eventually turn into beetles. The most common type of grub is the white grub, with the adult becoming a “chafer” beetle, tan in color. Another common type of grub is the May/June beetle. What’s notable about these two types of common grubs is that while the chafer beetle has a lifecycle of just one year, the May/June beetle has a cycle of three years.


Where they hatch and feed 

Grubs generally hatch on lawns that have been well watered, with eggs being laid on the soil in mid summer. The eggs will hatch and damage will occur beginning late midsummer, and may occur right up until early fall season.


Monitoring progress

 European chafer beetle has a lifecycle of just one year, while the June beetle has a three-year lifecycle. This may change how you want to manage them.


Noting damage

You’ll first note lawn grub damage by noticing that the grass will turn brown. It can be difficult to determine that this is actually lawn grub damage at first, because it looks much like many other things that can also occur at the same time of the year, such as short-term drought or drying of the soil.


Taking note of grubs’ stages of growth 

When first hatched, both June and chafer beetles are about 3 mm long, and can grow to sizes of between 2 and 4 cm at full larval stage growth. Beginning about late May or early June for June beetles and June to mid July for European chafer beetles, the beetles will begin to lay their eggs. By mid-June, May or June beetles’ eggs have hatched, and the larva will begin to feed on organic material. This is also true of the European chafer beetles’ larvae.


This is where the differences begin to occur between the European chafer and June beetles, though. With the June beetle larvae, the larvae move below the frost line to spend the winter and then reemerge in the spring when warmer temperatures arrive. Upon reemerging, they continue to feed. The same thing happens in the second year, with larvae moving below frost line when cooler temperatures arrive. They pupate in their third year, in June, after they have fed for a short time upon reemerging in the spring.


It’s important to note that with the June beetle larvae especially, it’s entirely possible to have larvae at different stages of growth below your frost line at any given time; that means that when you treat this particular infestation, you have to make sure that all stages of larval and adult growth are treated.


With the European chafer beetle, it takes one year for the beetle to complete its lifecycle, meaning that it goes through all stages in one year. The larvae hatch as long as there’s moisture present in the root zone, and can stay feeding until November or December. They move below the frost line, and then go back to grass roots and began feeding in early spring; they pupate in May.


Treating for lawn grubs 

Sample for infestation in areas you suspect it’s occurring in late fall, and treat then. It would be most effective then, as opposed to spring or early summer treatment. Formulations for insecticide treatments change all the time as new products come out, so check to see which are the most effective on the market at the time of treatment.



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