Grubs in Your Grass

Jul 26, 2017

      Lawn care and maintenance is on the fore front of many people’s mind at this time of year.  There are many factors that can contribute to the decline of a lawn’s health, from drought to lack of proper fertilization.  The topic for this article is a lesser known and commonly untreated issue of grubs.  Grubs are the larvae of beetles.  Most common in this area, the Northeastern US, are Japanese beetles and European Chafers.  Beetles are known mostly for the harm they can do to ornamental plants, while some may target very specific trees or shrubs, some varieties of beetle will indulge on upwards of 300 varieties of plants.  Unfortunately for turf owners, the beetles start early on to destroy the look of a property as the grubs feed on grass roots and can lead not just to a lean and unhealthy lawn but also large and unsightly bare spots.  This article will seek to describe the proper identification of and treatment for turf damage due to an over population of grubs.

      Having grubs in the soil is perfectly fine, when the population is kept in check.  A good suggestion for property owners who are attempting to identify why bare spots are showing up suddenly and may think its due to grubs is to take up about an one square foot by two inch thick section of turf and take a look underneath.  The first sign of an issue will be if the turf is easily removed, which would point immediately to an issue with the roots.  Once the patch is taken up, it should be flipped and inspected. Grubs are typically about one inch long, white, and in the shape of the letter C.  Now almost everyone has grubs in there turf, again the problem comes back to the population.  On a healthy, dense lawn, it is OK to have up to 6 grubs in that  one square foot patch of grass.  A leaner lawn can handle just a few.  If you are to find 10 or more grubs on one square foot of turf than you have identified that you have a grub population that is capable of destroying your lawn and it is time for some treatment.

      There are two forms of treatment for grubs; preventative and  curative.  While curative seems like the best bet because you are attempting to kill as many of the current grubs as possible, it is actually the less affective of the two options.  Preventative grub control will ensure that the following season you are still safe from the tiny invaders.  Because European Chafers often fly at night, by the time a property owner has realized a large beetle population exists it may be too late to deal with the grubs that have been  born beneath the soil or the eggs that can exist in several different area’s of a lawn.  Once the grubs have morphed into beetles it can be extremely difficult to get rid of them as the beetles are highly mobile, hard shelled, and may have already had new eggs.  The eggs are also quite resistant to insecticides and can be difficult to get rid of because of the locations where the rest before dropping into the soil.  Japanese beetle eggs will often times attach to the underside of leaves while European Chafer eggs are often hidden under hard and larger objects like wood piles or behind the bark of a tree.  The most effective time to get to the grubs are while still in their larval stage when the body is soft.

      The best time to use a curative insecticide is in September when the grubs have recently hatched and will be feeding.  Waiting later in the year means that the grubs will already be lower in the soil for their winter over.  The latest one should apply a curative is in the early Spring, before mid May, because once again the grubs will stop feeding and begin to turn to beetles which will then begin to appear in late June.  For preventative control, it is best to apply  from mid June through early August.  Preventive control refers to application prior to full hatching of the grub.  Preventative control systems often have a longer active time in the soil than curative and there for can be much more affective and less costly.  This is purely for controlling the overall populations of the grubs, there is no measure to take to completely eliminate grubs from the turf and there is also no need to eliminate them completely as mentioned before that a healthy lawn can easily withstand up to 6 grubs per square foot.

      A healthy lawn is the best measure against grub damage.  A mixture of a good fertilizer and a grub control measure used together is a sure fire way to protect your turf against these and numerous other factors that can destroy a lawn.  Our recommendation is several consecutive years of aeration and over seeding to create a dense lawn, consistent fertilization of the lawn and a grub control additive.  Other measure a turf owner can take are to keep the lawn at a 3.5-4 inch height when mowing.  Also, it is recommended to cut the lawn just prior to application of the fertilizer and grub control then to water the application in with about a half inch worth of water.  Cutting the lawn prior to application will cut down any flower weeds which in turn will keep bees away from the lawn and keep those bees away from the grub control which can kill them off as well (bees are important!)  Watering down the lawn post application will allow the control to get into the proper soil level to be most effective against the invaders.  We hope these tips keep your turf healthy and long lasting! 


Greg Young is the Director of Operations for Go Green Lawn Services, a local organic fertilizer company specializing in full scope lawn maintenance in the form of mowing, landscaping, fertilization and weed control, as well as commercial snow removal.  Based in West Chester, Greg supports a highly trained staff of technicians and laborers with commercial sales, operations, and logistics.  While relatively new to the company, Greg has over ten years experience in operations management, logistics, and sales. He can be contacted via e-mail at: Please click here to visit Go Green Lawn Services' website.




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