These ants are behaving very strangely... What the heck is wrong with them?

I was seeing a few ants around the house, so I put some Terro (ant poison that they take back to their home) down as a precaution. They left it alone for a full day, then suddenly I looked at it and they were positively swarming to it in two or three lanes instead of one. I had six helpings of Terro around the house and all of them were surrounded by ants. I just examined the ants closely and they are all moving very sluggishly and getting stuck in the crack they come in and out of and drowning in the Terro. It seems like they are brain damaged. I also examined the Terro, and there are bits of debris all around it wherever the ants can reach. It looks to me like they are depositing this debris into the Terro. I have never seen ants act this way and I have been using Terro for at least 10 years. I live in a duplex though, and the landlords are cleaning the place next door. I wonder if they could have given the ants something to make them do this, or do ants behave this way if their home is destroyed?