Alder leafminer on my Black Alders, Alnus glutinosa. These have been beautiful, fast growing trees planted from bare root last spring. They are adapted to wet soil and a lot of my property is either wet or heavy clay. These have been beautiful with shiny green leaves and small cones/strobiles. Right now they are being attacked by both Japanese beetle and Alder leafminer. The beetle is feeding on the leaves creating the lacy skeletonized leaf symptoms shown in the picture while the miner is leaving brown blotches all over the leaves. Not much I can do about either one of them without resorting to massive pesticides spraying so will simply ignore it. The beetle is about to lay eggs in my grass and die off and hopefully beneficial insects will soon respond to the leafminer and keep things in balance. Neither one really hurts the tree as injury happens late in the season after trees have had time to make planty of sugar. Oh well kinda ugly now but not that big of a deal. You really have to look up close to even notice it.