Holes in lawn & dying grass - Ask Extension
We aren't sure what is going on but there are these holes that are about a third of an inch in diameter along with several ant mounds. A neighbor fir...
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Holes in lawn & dying grass #460563
Asked June 07, 2018, 8:39 PM EDT
We aren't sure what is going on but there are these holes that are about a third of an inch in diameter along with several ant mounds. A neighbor first suggested that they thought it was a mole and grubs but we don't think that is the problem. We aren't sure how to treat it we live on a spring-fed lake and have a septic field and well.
Oakland County Michigan
Expert Response
Hello!
At this size, the holes were most likely caused by an insect. Without additional information, it's difficult to say what insect it might be--perhaps ground nesting bees or wasps, or even ants (without mounding). Are you seeing any specific insect activity in the area? Do you know when the holes first appeared?
As a reference, the article as this link has photos of the entry points of ground bee nests: https://entomology.cals.cornell.edu/extension/wild-pollinators/native-bees-your-backyard.
I believe that the insect burrowing is a result of the thin turf, rather than the cause. The insects are taking advantage of the direct access to the soil.
Some additional information about the turf might help sort out the problem. Unfortunately, that means I'm going to ask a bunch of questions. When did you first notice the change in the turf? How much do you water this area? How often and how much fertilizer do you apply? Have you had the soil tested? If so, do you know the soil texture? Does the area drain well? How many hours of sun does it receive?
This additional information will help in identifying the cause of the thinning turf. A photo of the problem area in the context of the whole lawn would also be helpful.
Regards,
At this size, the holes were most likely caused by an insect. Without additional information, it's difficult to say what insect it might be--perhaps ground nesting bees or wasps, or even ants (without mounding). Are you seeing any specific insect activity in the area? Do you know when the holes first appeared?
As a reference, the article as this link has photos of the entry points of ground bee nests: https://entomology.cals.cornell.edu/extension/wild-pollinators/native-bees-your-backyard.
I believe that the insect burrowing is a result of the thin turf, rather than the cause. The insects are taking advantage of the direct access to the soil.
Some additional information about the turf might help sort out the problem. Unfortunately, that means I'm going to ask a bunch of questions. When did you first notice the change in the turf? How much do you water this area? How often and how much fertilizer do you apply? Have you had the soil tested? If so, do you know the soil texture? Does the area drain well? How many hours of sun does it receive?
This additional information will help in identifying the cause of the thinning turf. A photo of the problem area in the context of the whole lawn would also be helpful.
Regards,
Thank you so much. I appreciate your help. We are new homeowners to this property for the last. 11 months. In the fall we noticed this same area in the lawn had something going on and now we have noticed this. We have noticed this issue for the past 6-8 weeks I would guess. This area faces South and gets full sun all day as tere are no trees in that area providing shade. Our septic field is underneath. We are on a well. Our sprinkler system uses water from the spring-fed lake that is in our backyard (the backyard gets quite wet). We haven't used the sprinkler system this year yet. We do not use any fertilizer.
There are ants everywhere in this area with lots of mounds.
We have not had the soil tested. The front yard seems to drain decently well. I am not sure of the soil texture. I can try to check tomorrow.
There are ants everywhere in this area with lots of mounds.
We have not had the soil tested. The front yard seems to drain decently well. I am not sure of the soil texture. I can try to check tomorrow.
Not sure if this is helpful or irrelevant but her are 2 pictures of what we noticed in the fall in the same area (now it seems to have changed to look like the previous photos I posted).
Hello again!
Thank you for the additional photos. Those from last fall show a pattern that matches the damage skunks and raccoons leave behind when they forage in the turf for insects and earthworms. Grubs are often the target food source.
I don't believe grubs are the current issue--there is little turf left in these areas to produce the roots on which they feed. Their feeding damage from last year, however, combined with the foraging damage caused by the mammals, may by the reason the turf died.
I would recommend re-seeding the area as your next step. I want to check on how to do this over a septic drain field, as I think it's a bit different than re-seeding a regular residential lawn. I'll send more information about that tomorrow.
Thank you for the additional photos. Those from last fall show a pattern that matches the damage skunks and raccoons leave behind when they forage in the turf for insects and earthworms. Grubs are often the target food source.
I don't believe grubs are the current issue--there is little turf left in these areas to produce the roots on which they feed. Their feeding damage from last year, however, combined with the foraging damage caused by the mammals, may by the reason the turf died.
I would recommend re-seeding the area as your next step. I want to check on how to do this over a septic drain field, as I think it's a bit different than re-seeding a regular residential lawn. I'll send more information about that tomorrow.
Hello again!
To re-seed this area, follow standard practice. Put down a quarter to half inch of fresh topsoil, spread the seed at the density suggested on the package, and rake lightly. The raking covers the seed with topsoil; it doesn't really move anything around. Cover the area lightly with straw to help retain moisture. Do not cover completely, as the grass seeds need light to germinate. To help get good germination rates, keep the area moist, but not wet, until the new grass gets established--typically until it's been mowed 3 times.
I was checking on two parts of this. Typically you do not add soil on top of a drain field, but this amount is insignificant. You also don't irrigate a drain field, but these areas appear to be small enough not to cause a problem.
Please let me know if you do see any specific insect activity around the holes. I'm curious about what caused them.
Regards,
Becky
To re-seed this area, follow standard practice. Put down a quarter to half inch of fresh topsoil, spread the seed at the density suggested on the package, and rake lightly. The raking covers the seed with topsoil; it doesn't really move anything around. Cover the area lightly with straw to help retain moisture. Do not cover completely, as the grass seeds need light to germinate. To help get good germination rates, keep the area moist, but not wet, until the new grass gets established--typically until it's been mowed 3 times.
I was checking on two parts of this. Typically you do not add soil on top of a drain field, but this amount is insignificant. You also don't irrigate a drain field, but these areas appear to be small enough not to cause a problem.
Please let me know if you do see any specific insect activity around the holes. I'm curious about what caused them.
Regards,
Becky
Hi Becky
Thank you for the information. We will try this. There are so many ant mounds around this area in addition to these holes. There are some fresh holes also in the last week or so that my husband noticed with marks that look like something was trying to dig/claw something out of the holes. Do we need to take care of the ant problem first before laying the soil and seed? We were thinking of setting up a camera to see if we can capture what is happening.
Also I checked the soil and it is sandy.
Thank you for the information. We will try this. There are so many ant mounds around this area in addition to these holes. There are some fresh holes also in the last week or so that my husband noticed with marks that look like something was trying to dig/claw something out of the holes. Do we need to take care of the ant problem first before laying the soil and seed? We were thinking of setting up a camera to see if we can capture what is happening.
Also I checked the soil and it is sandy.
Hello!
Thanks for the prompt feedback. Yes, taking care of the ant problem would be a good idea, as their tunneling might disrupt the rooting of the new grass seedlings. While the sandy soil makes the ants happy, it isn't good for new turf. I'll track down a septic specialist in the next couple of days, and see what they suggest to amend the soil before seeding.
Thanks for the prompt feedback. Yes, taking care of the ant problem would be a good idea, as their tunneling might disrupt the rooting of the new grass seedlings. While the sandy soil makes the ants happy, it isn't good for new turf. I'll track down a septic specialist in the next couple of days, and see what they suggest to amend the soil before seeding.
