Since many different species are having the same experience, I would wonder if it is a non-parasitic problem. Has your yard been exposed to any kind of polution, foliar fertilization or spraying?
hortster

Looks rather like stink bug damage.

Please list the specific plants with damage. And it would be helpful to post more images.

Might even be thrip damage. Hard to say.

Thanks everyone, much appreciated! I have no idea how to post more photos or how to display the current photo rather than just a link. Any help would be appreciated.

There are many plants in my garden that I have no idea what they are, however the ones I can name are: foxglove, cat mint, rose, clover, oxalis, sage, majoram, oregano, morning glory.

Sorry Horster, no pollution or spraying in the garden.

I've included a link to the photos I've taken on various plants.

Here is a link that might be useful: my plant disease photos

Sorry Horster, no pollution or spraying in the garden.

Have inlcuded a link below containing pictures of the various plants that are affected.

Here is a link that might be useful: my plant disease photos

What has your air quality been over the past month or more?

I think I may have found the culprit, a small insect of about 3mm long that looks like a mini grasshopper. It's pale and has a camoflage-like pattern. The small ones hop, the full grown ones fly, anyone have any ideas what this could be? Sorry no photos, my camera isn't sophisticated enough to take pictures of something this small.

Leaf hoppers, more than likely. A very common pest that can be found on a wide variety of plants. At least, that's my best guess from your recent description.