They look like they might be droppings. Are there leaves above that are being chewed on? Looks like something is munching on this leaf. I would guess that whatever is eating the leaf is leaving eggs or droppings.

Hi, Bree

Great job to be able to get so many cukes developing right now!

I looked up cucumber pests and it looks like you have squash vine borer frass on the leaf. There's also the pickle worm, which is what got my vining veggies.

After looking at the website that describes all the problems cucumbers can get, I am not thrilled about trying them again!

So I love that yours are doing well and hope you get all those cukes to the table!

Susie

Looks like caterpillar frass (droppings) to me as well - try looking above this spot or on the underside of that leaf - which looks like it may've been chewed a bit along the edge. There are some green caterpillars that hide themselves along the veins on the undersides of leaves, as well as some that fold a corner of a leaf over & secure it w/ silk to hide in.

FYI, most insect eggs on leaves are 'glued' down & cannot be removed easily.

Thank you! Should I get rid of the leaves with the caterpillars on them? Or just try and remove the caterpillar?

I just squish the caterpillars w/ my fingers or between the folded leaves.

I was just listening to Tom McCubbin on his radio show and he suggested it was time to get rid of the plants that had these borers. Personally I have no experience.

You can spray or dust w/ Bt as well, but it needs to be applied often when it rains every day or so, since that washes it off. I use Thuricide - sometimes - but I'm kind of lazy, so I often just handpick instead. It really is past cucumber season for me, tho it may not be, if you're further north.