Something cutting/eating dendrobium

[Orchitty]

Hi guys. Last week I noticed that something had "cut" a young leaf off my dendrobium. One of the shoots also looked like it had been snipped across the top. Didn't suspect bugs because the cut looked so even and clean like it had been cut with scissors. Yesterday, noticed another shoot and leaves with curved bites and a hole. Brought the plant in from my second floor patio and sprayed plant and medium heavily with Dr. Earth Insect Killer (natural oils) hoping to draw whatever it was out. Nothing came out of medium or moved on plant. This morning, also soaked the medium in water with nothing coming out. I've noticed one or two dead white caterpillar/grubs in my water containers on the patio a few times. Could it have been caterpillars? None of my other orchids seem to be eaten. Thoughts? Experiences? I live in NE Iowa btw. Here are some pictures.