Hello Zoë,
That link does have its problems. That first picture is of a grasshopper. I don't know that being an Amazon Associate discredits you as knowing anything, but I concede that that link oversells the carnivorous aspect of the katydid diet. This is a different what-do-katydids-eat link:
https://imp.world/animals/what...
There are supposedly 255 species of Katydids in North America, and thousands worldwide. I don't know how many Katydid species we have here in Kansas. I frequently see Katydids on my zinnias, and I have never seen one take a bite out of any part of a zinnia plant. I have seen Katydids eating small insects off of my zinnias, consisting of aphids and other small insects, and once a small flower spider. So as far as I am concerned, the Katydids in this part of Kansas are beneficial. At least, slightly beneficial to my zinnias. I have no idea what they are eating when I am not watching them. Possibly tree leaves or parts of some of our many native plants. I agree that Katydids are not exclusively carnivores, but are probably omnivores. I do enjoy their evening songs.
"You might have a different species."
Based on different appearances, I have at least two, and possibly three, or more different species of Katydids. Part of their diversity may be significant differences between katydid males and females.
Anyway, I don't think we have any serious disagreements on Katydids.
ZM
