Trees with random batches of leaves dead

We have some trees on our property that have recently started showing some issues, specifically, random batches of leaves dying on the branches. One tree has been here since we built the house, 12 years ago, and it's never had any issues. It's some kind of crabapple if I remember right, the fruit is very small though.

The other two trees we planted two years ago when they were very small, and they are an oak tree.

We live in Calgary Alberta canada, and we've had a VERY wet spring/summer with good heat when not raining.

Your thoughts are appreciated,

Thanks

Hi Rob- the wilted/dying twigs on the crabapples might be cicada damage- do you have them that far north?  

Tom,

We don't have cicadas up here. Thanks for your thoughts though

"Cut worms"? Looks something like what we have each year on a couple large Maples in the Chicago area. Local arborist said it's common. The trees don't seem to be suffering too much from it, but it's annoying to mow up small branches every couple weeks.  Guess it'd be a moth larva of some type. Didn't take it further - too much else going on.

FWIW
Rufus