What are these white things?

[NatJ]

Have you tried to squish a piece of it? Is it hard or soft?
Maybe cut one open to see what's inside it?

Since you don't have any chickens there at present, you could wait a few days and see what happens--it may disappear, or there may be more of them, but either way you might learn something from what happens.

Right now, I could guess: small bits of foam packing material, some kind of chicken treat, bugs or their eggs, pollen or seeds from some plant, something pelleted that's meant to kill pests (pests being bugs, weeds, rodents, etc), a funny-shaped calcium supplement... the options are apparently endless.

Personally, I would not go spreading anything that kills "everything" until you are able to figure out what you've got. And anything that kill only some things, might not address this. (And the thought of trying to kill foam, or tree seeds, or rat poison )

 

[JanR1]

What does the building look like? Is it wood? The floor is obviously dirt or awfully dirty. What came to mind when I saw it is dead termite larvae. Maybe they found termites and sprayed because they were selling and wanted to get rid of the evidence. Do you know anyone brave enough to get close to it with a magnifying glass? That might help some.

 

[BaaKaaawk]

How long would I need to wait to introduce my flock to the area if I seven dust it? Thank you so much for replying and the encouragement!

Some people put 7 right on their chickens (as noted below) so you would not have to really wait long at all.

i actually spray the liquid 7 on my chickens... i read that its fine.... really takes care of the gnats when they get bad... any body ever heard of it harming chickens? im not sure about the dust tho it could get in their feed and stuff but i guess you dont have any chickens yet sooo it should be fine....

Yes, I have heard it harming your birds and I had one of my favorite TopHat roosters die the day after I seven dusted all my flock (no proof it was the Seven, but seems pretty suspect to me). From that point on I used "Poultry Dust" which is specifically designed to put on your birds. Never had an issue since, been about 10 years now.

 

[Eggcessive]

I would just do a good sweeping and cleaning. No need to go ballistic, but just try to sweep up the bits and dispose of them. Then add some sand to your coop flooring. I am going to tag @dawg53 just to have a look at the pictures in post 1, to give his opinion on what it looks like. I am still leaning toward dead maggot larvae, but hard to positively know for sure.