I'm looking for any recommendations on dog/environment friendly flea treatments for the yard. I have some DE for gravel and concrete areas and will stop at the garden center to get some nematodes for the grass. Any other suggestions? Has anyone used this type of spray before https://www.petco.com/shop/en/petcostore/product/natural-chemistry-yard-and-kennel-spray and did it work?

After being in my house for 13 years with no flea problems I suddenly discovered little black specks on my ankles yesterday and the day before... I highly suspect they have migrated over from next door. The neighbors adopted a dog late last year and the poor thing is either hiding in their back yard or roaming the block I don't think they spend any time or attention on it and I doubt it's receiving any type of flea/hw preventative. I have no idea why they even got a dog; we have zero relationship because they won't answer the door or talk to us...

I have Greta on trifexis and went to the vet yesterday for a single dose of nexguard hoping that it only takes us a month to figure something out (we have done this in the past per his recommendation when going to visit my parents during tick season)... if this is going to be a long term battle we may have to consider changing what she's on, though. My understanding is that the trifexis prevents eggs from hatching while the nexguard kills active fleas that bite; I guess there are only one or two options for active fleas that you can combine with trifexis safely.

How annoying! Any suggestions would be much appreciated.

Hi Carolyn. Sorry I have not much experience with chemical fly repellents.
What helped my own outdoor dogs are: Strict environmental cleanliness and for the dogs themselves regular grooming and washing the fur with a mixture of Apple Cider Vinegar and water. Additionally I add daily some ACV in their veggie glop. Since doing this the flies are not attracted any more. We have two Pits and a short-haired stray, who are of course much easier to groom, than long-haired ones. But it works also for my rather thick-haired Lab-Mix.
This method also keeps midges and ticks away, which are horribly nasty here.

Until now I've never used one of the various oils or the petroleum jelly which are also recommended on the following links, so I can't judge this. But I think it would be worth trying, if necessary.

https://www.wikihow.com/Keep-Flies-Off-Dogs
https://pets.thenest.com/home-remedy-keep-flies-off-dogs-6084.html
https://herepup.com/flies-on-dogs/

Thanks for the response, Christina. I'm afraid I was looking for advice on fleas, though, not flies.

Since my original post I purchased some of the essential oil based stuff (link in my op); it smells great! We'll see if it does anything for the fleas, lol.

Sorry, Caroly, for confounding the two words (my English!!). Maybe you have found in between something useful.
I've searched in the internet and found some sites, which might give us some use ful advises.
https://www.dogsnaturallymagazine.com/how-to-get-rid-of-fleas-naturally/
https://www.thedodo.com/close-to-home/get-rid-of-fleas-on-dogs
https://www.fleabites.net/7-ways-to-naturally-get-rid-of-fleas-on-dogs/

I know someone who uses regularly NexGard and is convinced of it. I myself have no experience with it. But as one of my dogs scratches herself more often as normal, I will have to keep an eye on this. I too don't want infested dogs, nor my yard, nor people living there. Fleas can muritiply extremely quickly once the succeed to put their eggs somewhere. I think it is worth it to be very careful and attentive.