I'm much further south than you, they come by in the spring and then their pretty much gone until September down here. I see them in the Summer up at our house in Midcoast Maine. Seeing them in the beginning of August around here is rare. I agree though, they are in serious decline and I hope with the increases in Milkweed that they rebound.Larry, your recollection is off. Monarchs arrive in the North in Spring and leave in the Fall. Unfortunately, the fact that you are just seeing one is testament to their decline.
I have seen far fewer this year despite the abundance of milkweed. J