Great Lakes - What is, Little purple dots?

Only second year docking and early in the season there are these little purple dots all over boat. It has to be some droppings from something. I know I won't be able to stop it but just want to know what it is. Plus it's not the easiest to clean so if you have a cleaning product idea that can be used and safe for environment.
And bird $hit, would love to hear people's solution to clean it off. I get the main part off but others times it leaves a shadow of where it was. I get it clean but takes forever.
Wife tells she wished I cleaned everything as much and well as I do the boat.

Spider crap?? It is a pain in the ass to clean!

That would be the easiest explaination but the marks are not in spots were you ususally get spider poop. It's all over not just under spider hiding spots. Plus I havent seen a spider on the boat, yet.
Midge droppings?

Around my area, the muffleheads leave small usually greenish dots behind everywhere.

Well now that I think about it the color could be green. I would have to agree that the latest markings have been all on the south side of the boat. I imagine from the northly winds lately.

Bird crap: 50% simple green, 50% bleach (1cup each) top off bucket with water, add a dash of bartender's helper and scrub with a soft brush. I use 1 bucket to clean the whole boat at least once per week and have been doing it for more than 10 years. No need to go back over things, gets the spider $hit too, and rinses crystal clean from glass.

It's mufflehead poop. Try Soft Scrub w/bleach.

yup, there was a big bug hatch on saturday. rub a dub dub, scrub a dub dub. those "magic erasers" by Mr. Clean will remove about anything, FYI