Grub Control Can be Confusing and that’s Not Really a Good Thing.
Driving to work this morning I noticed that my local neighborhood hardware store had put up some new language on their display sign. Since the snow from Friday’s April Fools Day storm has just about melted many of us in Southern New Hampshire have begun to think about treating our lawns. Advertisements for different types of lawn care products have increased ten fold as we put the winter behind us finally.
Let me say this before I begin, County Stores, the store who is advertising the Scotts 4 Step program is one of my favorites. It has old fashioned service and you can get absolutely anything you need. I bypass the big box stores often to spend my money here. Secondly, The Scotts company is obviously one of the most historic and celebrated lawn care corporations in the country and although they are likely one of the largest purveyors of pesticides in the world I don’t mean to take any particular issue with them right now either. It’s the advertisement for Grubex that has me a little bit worried. The control of grubs in home lawns is a very important part of lawn care. It’s my opinion that we’ve gotten a little bit carried away with our absolute dependence on preventative pesticides to deal with them but again, that’s not my point here. I saw the sign and thought it may be a good time to do a quick version of the “life cycle of a grub” essay. The main reason is this, no matter what type of control product you are using for grubs this year, none of them are going to work if you apply them now.
Grubs are the larval stage of any beetle. They are typically white worms that feed on the root system of your lawn. In some cases a severe infestation of grubs can destroy large swaths of turf if they are left untreated or go unnoticed. Grubs are probably second only to crabgrass when it comes to enemies of a nice lawn. When trying to explain the life cycle of a grub it usually makes sense to start with the time of year when they are actively feeding on turf and doing the most damage. However in this case lets start now in the spring.
In the spring grubs come to the surface of the lawn where they prepare to make their final metamorphosis into a beetle. Whether it’s a Japanese Beetle, a European Chafer Beetle or a June Bug Beetle, grubs are simply not feeding in the spring time therefore they can not ingest any insecticide that has been applied to the lawn. As temperatures continue to warm, the grub will become a beetle.
Summer is the time of year when beetles can do damage to plant material other than the lawn. They feed on vegetable gardens, any green leafy plant and trees and shrubs. It’s like one big party for flying beetles this time of year not only because they are eating like crazy but because they are mating like crazy too. This is the time of year when the life cycle of a grub truly begins. Beetles will mate in the summer and lay their eggs in turf to begin the whole thing over again.
Grubs typically hatch towards the end of the summer and begin to feed heavily on the roots of the turf in the early fall. They can continue to do damage, often unseen deep into the fall and can wipe out a lawn with ease. The turf may become discolored and can pull up like a carpet as the root system is decimated. It is during this feeding period, especially in the beginning when grubs will ingest anything designed to kill them such as a pesticide. If they go untreated they will burrow down in the soil as far as they can to escape cold temperatures and then surface in the spring of the following year to start the process over again.
The point is this, do NOT apply anything to your lawn to kill grubs in the spring time, especially a systemic grub insecticide like Grubex. Grubex will not become active until about a month after it is applied. (by active, I mean part of the tissue of the root system of your lawn, that’s what I mean by systemic, as opposed to contact insecticide.) By the time the grub control is working there are no grubs in the lawn. Secondly, it will have a residual of only a couple of months, so that by the time the next generation of grubs are feeding on your lawn in the Fall, it will be gone. Perhaps this sign is advertising grub control for use in a couple of months when it is most likely to be effective, I’m not sure, but if you are going to employ the use of chemical insecticides please be aware of the most effective ways to use them.
More on grubs in your organic lawn later in the week.