You should firstly try to tell them not to do this or else you will make a complain to the building authorities. Then if they do not take it seriously do complain with evidence

 A. I had a similar situation with my u/s neighbors except I did complain and nothing ever changed. So decided to be more direct and assertive. I kept a journal of things I considered were intolerable to live with. Took about 2 weeks to fill it. Then I typed a letter to the local police authorities indicating all the legal info re: names, addresses followed up by the actions I had already taken, then a list of what I wanted to stop. Then I wrote a note to the apt mngr, asking her again to enforce their compliance. And enclosed a copy of the letter to the police dpt. Within one week, my neighbors were arrested for dealing drugs, ultimately convicted, and finally evicted and tossed out forcedly. We all slept better after that.
I would fist drop these folks a note asking them to stop (in case they didn't know they dropped trash or the honey in your area??) Gives them the chance to save face & correct by just playing dumb. Ha! we know better. A note is safer than approaching them on your own, plus added evidence. Tell them you will go to the mngr. Possibly mention you would install security camera. But keep in mind, unless you want or can move right away, you will have to deal with them daily, sometimes under very bad conditions, with no avail. So you would be prudent to treat them with kitt gloves and approach cautiously. Good luck!