Ingenious Steps to Control Grubs and Cutworms

From 2001 to 2006 the TV show Fear Factor grossed out their audiences challenging contestants to do hideous things the average human wouldn’t think of doing.  One of the top dares was eating what eats your lawn – grubs!  Although the TV show has been canceled, grubs and their counterpart’s cutworms, are always on the lookout for the tasty grass and roots.

Southern California has the longest growing season on the planet.  Due to mild seasons, this means turf insect activity is prolonged, sometimes all year long, and insects just love that!  Grubs and cutworms are notorious for chomping on lawn roots and must be dealt with swiftly.  Today we’ll identify grub and cutworm damage and how to deal with it.  Plus, you’re going to be surprised what these ravaging creatures turn into.

What is a grub?

What is a cutworm?

In general, grubs are creamy white-colored larvae of many species of adult beetles (like those iridescent green beetles).  They can grow up to 2” long but curl up when disturbed.  Their main diet is lawn roots and decaying organic matter.  They are most active in the evening.Typically cutworms are more caterpillar-like in varying colors from brown, gray, yellow, and with stripes. They are the by-product of grey moths. In their young stage, they’ll eat roots.  As they become older they’ll rise to the soil surface and “cut” the stem off.  Damage is done at night.
Note:  Be lucky we don’t get Hercules Beetles in our neck of the woods. 

Those grubs can grow larger than your hand and will try to wrestle you to the ground!


For our purposes, we are going to lump the two species together.  Control crosses over to both.  Either one can be just as lively as the other and their damage is quickly noticed by yellowing grass and irregular dead spots.  Sometimes the damage may look like a fungus so identification is paramount in eradicating the beasts.  Take inventory of your lawn before mowing for any problem areas.  It’s easier to notice the damage when the grass is a bit longer.

Control by Critters.  If you didn’t open a petting zoo and opossum, skunk, raccoon, and birds are poking around the lawn scratching and digging you might want to let them have at it.  All of these critters are keen grub and cutworm hunters.  Of course, using these helpmates opens up other lawn problems like digging up grass and holes in the lawn.  But, for the tree hugger, it’s a chemical-free option.

IPM Control. Speaking of chemical-free options, Integrated Pest Management (IPM) is an amazing approach to controlling all sorts of insects.  The idea is to use organic and natural tactics.  The only downside to this is IPM normally isn’t selective.  If there are any good bugs, like predatory ants, ground beetles, rove or blister beetles, springtails, and millipedes – they’ll get zapped by IPM controls.


Pro-Tip:  To verify grub and/or cutworms slice off the bottom of a coffee can and wiggle it into the soil a bit over part of a damaged area and split the difference over part of a good area.  Fill the coffee can up with water.  Within a short time, you should see the larvae float to the surface.  Remember, they are active in the evening so hunt for them in the dark.


Bug juice is an extreme IPM control that can be entertained with little to no worry about killing off good bugs.  The premise is that you’d have to corral adult moths or menacing beetles in their egg-laying stage.   For instance, grey moths are active in summer as the sunsets.  Collect as many as you can with a butterfly net then play the Grim Reaper and put them in a permanent state of slumber.  When handling insects an instinct is for them to excrete a natural warning scent telling all the other bugs of the same species that danger is around and to stay away.  It’s kind of like the opposite of a pheromone.  This works in your favor because now you want to play taps as you put the insects in a blender with a cup of water and hit puree.  The warning scent will infuse with the water.  The next step is to strain the body parts with cheesecloth then put the concoction in a hose-end sprayer to spray your lawn.  With the warning scent distributed throughout the yard cross your fingers the insects heed the warning and move to your neighbor’s yard.  When working with bug juice you’ll have to do this after each time you water you lawn because you’ll be washing off the insecticide.  This is common when using the IPM approach.

Natural organic lawn food is a secret to fighting lawn insects.  When a lawn is healthy it can withstand tons of abuse.  If you start right now you’ll be able to strengthen all lawn parts above and below the ground and it’s so simple to do.  All you have to do is schedule regular fertilizer applications throughout the year.  Once it develops into a routine the chore turns second nature and it isn’t a burden any longer.  And, the best part is with natural organic lawn food you can get sloppy with it and share some love with planter beds, flowers, plants, trees, and even vegetables.  We want all of your yard and garden to look good.

Chemical Control.  Formulation scientists researched for years investing millions of dollars to bring lawn herbicides to the marketplace.  It’s their duty to create safe products that will exterminate the target insect, making it safe to use and have the ability to maintain an insect-free turf for months at a time.  For southern California no more than two applications a year is needed.  In fact, some formulators have a once a year program when Imidacloprid is the active ingredient.   The mode of action is that when Imidaclorprid gets watered into the ground the roots will absorb it then grubs will take a bite, feel full then die from starvation (science is so cool, right?)

You can find grub/cutworm herbicides in a liquid form but the most popular way is in a granular form.  They are delivered through either a drop, broadcast, or hand spreaders. Unlike granular fertilizer, you don’t want to touch it and spread it out by hand.  It can be absorbed by the skin and I’m certain body parts will begin to fall off – so be careful.  Since masks are still fashionable it’s not a bad idea to wear one.  Even though the herbicide bag has a tiny print always take the time to read the label for safety precautions and that you are targeting grubs or cutworms.

Nick Federoff
Award-winning radio & TV garden communicator

Contact to Listing Owner

Captcha Code