Hello,

From your picture, I notice there is damage along the outer edges, as well as the interior of the leaves.

There are a couple common insects active in our gardens right now that munch outer edges as well as make holes in the middle of leaves. Grasshoppers typically leave irregularly shaped holes, like what you have on your zinnias. If you observe grasshoppers on the plant or elsewhere in your garden, this could be one of your culprits. Unfortunately, it’s difficult to control grasshoppers and their damage because they are so mobile. Here is a fact sheet about grasshoppers in the garden. https://extension.colostate.edu/topic-areas/insects/grasshopper-control-in-gardens-small-acreages-5-536/ 

Caterpillars can also leave irregularly shaped holes on the interior or exterior of leaves. Earwigs will eat blossoms and leave irregular shaped holes. Healthy plants can withstand caterpillars, earwigs, and grasshoppers. It may not look great, but unless it is a major infestation, they won’t kill a healthy plant. To control caterpillars you can just pick them off your plants if you see them. Find more information about earwigs in the link below. The link details how to create a simple earwig trap. Earwigs can be a pest, but also feed on aphids and mites so if the damage to your plants is not too extensive, you may want to let them be. https://extension.colostate.edu/topic-areas/insects/european-earwigs-5-533/

You mention you have some japanese beetles, and I have noticed Japanese beetles on my zinnias as well. While it's not their favorite food, they have caused some minor damage. However, the damage in your pictures does not look like the damage caused by Japanese Beetles. Japanese Beetles chew the leaves in between the veins and skeletonize the leaf.

One of the spots on your Black Eyed Susan looks like an almost perfect semicircle. This is indicative of a leafcutter bee. While you may not like them cutting up your flower petals, they are a non-aggressive, important native pollinator and are using the pieces they cut to build their nests. Here’s some fun info. about leafcutters: https://extension.colostate.edu/topic-areas/insects/leafcutter-bees-5-576/

Overall, it’s normal to have insect damage to plants and flowers in the garden and you probably have a couple different types of insects at work. Healthy plants can withstand minor pest damage.

It’s possible you have different insects feeding on your elm, however. There are a couple insects that feed on Elm leaves: The European Elm leaf weevil and Elm leaf beetle. The Elm leaf beetle can cause significant defoliation of the tree. Here is a fact sheet from CSU with information about both insects: https://docs.google.com/document/d/17R1PETayyPy6vhXfMZetk1L1rwNIspP-OG_ibPgbY88/edit#

The University of California states: “Elm leaf beetles, when abundant, can entirely defoliate large elm trees, which eliminates summer shade and reduces the aesthetic value of trees. Repeated, extensive defoliation weakens elms, causing trees to decline.” But their fact sheet (see link below) also states the Chinese Elm is moderately resistant to Elm leaf beetles. If you are seeing large amounts of defoliation in your tree, this would be cause for concern and would warrant identifying if you in fact have these pests in your tree. It is not advised to control for the pest unless you know for sure that you have it. Both fact sheets have information about how to control this beetle. http://ipm.ucanr.edu/PMG/PESTNOTES/pn7403.html