Hey Si, Pests are much more likely to get on weakened trees, in the little I know about Maples, is that they need aa fair amount of sunlight, so it can thrive nicely before autumn comes in, only minding about covering it if temp. rises above 30ºC.
I used to live in a appartment, now I live in a home, back in the day, my plants was all on a balcony, yet I had a lot of problems with Cochineal and Aphids... Nowadays, ALL my plants are outside spreaded tru' the garden/patio, alongside with fullsize trees, grass and others... Still, I have close to zero cases of pests...