Thanks for the question.

I suspect that this is a yellow jacket nest.  They nest in the ground and at this time of the year they greatly increase in numbers and become quite aggressive.  They can sting multiple times and generally do this as a mass.  Now would not be a good time to deal with this problem unless you hire a professional exterminator.  This certainly would be an option.  This entire colony except for the queen will die once we get a week or two of night temperatures below 45 degrees.  For this reason,  there is no concern that they will enter your house.  Sometime in late October you should dig up the entire nest.  All of the yellow jackets will be dead or immobile at that time. The reason for digging up the nest is to remove the queen should she still be present.  Also it will discourage yellow jackets using this nest in 2020.  

You may the following to be of some interest:

https://www.beelab.umn.edu/public-concerns/bee-removal

https://www.beelab.umn.edu/sites/beelab.umn.edu/files/bothered_by_bees_wasps.pdf

https://extension.umn.edu/insects-infest-homes/wasps-and-bees#yellowjackets-and-baldfaced-hornets-1464410

Good Luck!!

Hi Steve! This is great information to have, thank you! However, I am concerned about them entering my home because last fall I had MANY enter my home. They were mostly in the basement and they were sluggish and dying, but I don’t want this to happen again. They did manage to dig through the Sevin dust and reopen the hole to the nest. It has been over 24 hours and they’re still quite active. Please let me know if you have any other thoughts or advice. Thanks!

Thanks for the response.

As temperatures cool, yellow jackets' natural response is to seek warmth.  So there is a possibility, as you observed last fall, that some may enter your house.  I do get yellow jackets in my house every fall.  However in your case it would not be possible to distinguish between those coming from nests in your yard from those coming into the house from adjacent areas.  To some extent it is unavoidable.  The fact that you observed these in your basement makes me suspect that they might have entered through your basement windows, assuming you have such.  If this is applicable, check for openings along the inside basement window edges.  Check around spaces around any utilities (gas, water, electrical, etc)  entering through your basement walls.  

I am not surprised about their reopening the hole.  Yellow jackets get rather stressed this time of the year about their impending demise.  Egg laying by the queen is tremendous - up to a thousand eggs or more per day.  All of this requires food to feed the emerging workers.  They will always find a way out of a plugged nest.  While the Sevin may kill some workers,  this will be a small drop in the bucket in terms of the numbers of new workers being produced every day.  You simply cannot keep up with them.  Again my suggestion is to just let them do their thing but give them a wide berth.  They days are numbered.

After I initially wrote you, I did a little more research on old nests.  The literature suggests that rarely will yellow jackets return to old nests.  In fact our cold winter temperatures typically lead to a disintegration of the entire nest.  So ignore my suggestion about digging up the old nest in October.  It probably is just not necessary.

One other point and I hope that I do not offend you.  Yellow jackets just love spiders.  So in the off chance that you have resident spiders in your basement, that would entice yellow jackets in.

Good Luck!!