Please tell me how to cure this. There was never a problem until I purchased a bird's nest fern, and put it near the Philodendron , just 5 weeks ago.

It could possibly be mites. I would move the fern and philodendron way from the rest But still treat everything. If you wipe under the leaves with a whi paper towel and see orange or reddish residue suspect mites.

Trat with something specific to mites. Regular insect spray won’t work on mites.

Hi James,.

Thank you, but definitely does not look like mites. No orange when wiped after a good application of soap and oil spray, and there were quite a few of those tiny black specks, like in the first photo. Really tiny. I am not sure they were all insects. Some were moving.

Forgive the shine in this photo... still wet from the oil and soap. You can see the leaf before I wiped away the black specks.

Looks like a combination of scale and leaf miner.

I agree, you need to post a pic of the whole plant, tell us where you live and whether this plant is growing indoors/outdoors.

Jane

Thrips. Use a systemic Imidacloprid.

yep, it's thrips. the eggs are embedded inside, the larva hatches and chews inside the leaf, making those markings(leaf miner channels are larger and far better defined). then they molt and crawl out : narrow bodied brown or black.

they continue feeding on the leaf. then they change again into flying insects and spread around. they get used to systemic fast and it stops being effective. and you'll need to switch to different systemic..so you need to isolate the plant and treat fast.