fly infestation

Asked March 19, 2018, 9:03 AM EDT

Hi, I bought a house in August. It is in an underdeveloped neighborhood (Deanwood) and the house was newly built. The yard came with grass sod installed. During the first months we were surprised to realize that a lot of stinkhorn mushrooms were growing and that there were lots of flies permanently hovering, especially at the ground level. These are small-sized flies. When my husband and I went to do some landscaping work about a month ago, we discovered that the lot had not beed cleaned at all before placing the sod. So right under it there were weeds and some trash, and buried further down a lot of rubble (bricks, cinder blocks and chunks of cement) from a house that used to be on the lot over 20 years ago. We also found large amounts of trash (tiparillo flters, plastics, candy wraps, broken glass, rags, bits of sweater, tin cans, etc....) The soil also smells a little bit, though not everywhere and not terribly badly. It's not a sewer type smell. I believe the flies might be related to all the trash we found below the grass. We tilled the entire yard and filtered the soil. There are still small amounts of glass around as it's impossible to remove it all, but we're ok with that. I have no idea how to proceed now. Should I test the soil? Can these flies be exterminated somehow? What about the stinkhorns? I don't want to go on with the actual planting before knowing if I should do something else.... THANK YOU!

District of Columbia County District of Columbia sod lawn and turf new lawn problems sod over debris sod laid over organic matter

5 Responses

Interesting situation. The flies are probably a result of a lot of organic matter decaying under the soil, but we can't say for sure since we don't know what kind of fly it was.
The stinkhorn fungus is completely harmless, but it is a fungus and grows on dead organic matter, so they, too, point in that direction.

Organic matter is not bad, in fact it is a component of good top soil. When a wooded lot is cleared, there is usually a large amount of dead roots in the soil which will ultimately decompose and feed the lawn and other ornamentals you plant. You may see a mushroom occasionally, but that's not a problem. There should be no smell except a good healthy soil smell, however soil that stays wet for long periods can smell unpleasant. That would be a drainage or grading issue.

We would encourage you to have a regular soil test to see if the soil needs nutrients and also see if the pH needs correcting with lime. Here is our webpage on soil testing: which explains how to collect a soil sample and where to send it.

We have an abundance of information on successful lawn establishment. Here is a great primer that explains a lot and can save you from many problems:

Feel free to ask or send us photos with any problems.


Thanks for your response! About the flies, I'm not sure what type they are, but my husband claims that they seemed to be burrowing into the soil, probably laying eggs or something like that. There really is a large number of them, which makes it annoying to be outside. Do you know of any effective fly elimination method that is not environmentally harmful?

Flies are not normally a problem in lawns. No, we don't recommend doing anything or applying anything without an id. Even safe lawn insecticides are going to have unhealthy impacts on the organisms needed for establishing a healthy lawn.

If they show up again, send us a photo.


Ok, thank you! As soon as it gets warm, I'll see if we can identify them and/or get a photo.