Looks like spongy moth caterpillars are probably the main issue. I believe parts of central PA were expected to have relatively high numbers of them this year. If the caterpillars are still small they can be controlled with Bt.

Thanks for the feedback. What is Bt?

Bacillus thuringiensis, a biopesticide.

contact your local county extension office.. and see if they recommend any action... like some local plague we dont know about....

welcome to the forums.. there are at least two other posts down the page addressing the same leaf issues..

to be very clear.. 99.9 % of your leaf is working just fine.. converting sunshine into energy ... there really is no reason you need to do anything other than kill every insect on the tree.. good and bad...

its a deciduous tree.. it will lose these leaves in fall.. and you may never see this issue again.. or maybe in 10 years.. its just really nothing to worry about..

and odds are.. the bugs are already gone.. and if you do spray or something.. you are basically just polluting .. unless you can find and clearly ID a pest.. you should not do anything....

ive had mid summer hail storms just about denude maples trees.. and they can do do releaf..

there is going to be no long term harm to your trees.. for a few ugly leaves..

to come full circle. plagues come and go over the decades.. and so what.. dont panic...

ken