Billbug vs. Grub vs. Drought (How to tell the difference)

Kalie Larkin Expert Advice, Lawn Care Leave a Comment

Pools have opened and summer is here! This also means the grubs have come calling to many of our friends and neighbors but (hopefully) not to us. One of the hardest parts of grub detection is knowing whether or not you have grubs, drought or a bit of both. This can be a bit tricky because it’s possible for them to have similar symptoms at first glance. Aka a yellowing of the turf right in the hottest part of summer.


There are two quick tests that will give you a good idea as to what is causing the problem. Walk over to several of the spots that are turning yellow, reach down, grab a big handful of turf and give it a tug. If the whole handful starts to lift out below the surface there is a good chance you have some form of grub(or in our area, billbug) infestation. The turf pops up below the surface because the larvae feed on the roots.



The term grub is often used to describe a particular set of symptoms that can be caused by the larval stage of several different insects. We have two main categories: c-grubs and billbugs. Billbugs are the one that we see causing 95% of our “grub” symptoms. Adult billbugs are actually known as weevils. You can see them crossing sidewalks or any other hardscape surface between spring and late summer. They are generally black with a long “nose” and hard shell. Their larvae are white with a dark brown to orangish cap at one end and are about the size of Abraham Lincoln’s chest on the US penny.

C-grubs are the ones most people think of when they are told they have “grub damage”. They are white, much larger than the billbug larvae and form the classic “C” shape. Their adults can be one of many types of scarab beetles: Masked Chafers, June Beetles and Japanese Beetles are just some of them. They have a very distinctive life cycle from the weevils, aka billbugs, and will have a separate timing on treatments.

Going back to the tug test, when you tug on the yellow spot and it doesn’t come up or if it rips off at the surface you might be looking at a drought spot. This is where you move to our second test. It is also really simple, you just pull out a long flat head screwdriver. Try driving it down into the middle of the yellow spot. If it goes in fairly easily then you know you are getting a good watering depth. If it won’t go in very far or at all then that spot definitely needs more water.


Make sure to test out several areas in the lawn before coming to a conclusion. I have been to many a lawn in the middle of summer and found one spot is dry while another spot has a patch of billbugs. The most important part is to not make any assumptions about what you are seeing!


If you have any questions or would like a free estimate please feel free to call us at: (208)523-5296!

Contact us if you’re looking for lawn care services in Idaho Falls, Idaho

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