Mildew

You are like a minute fungus

An enemy waiting for us

To leave food out in a damp place

And then you will show your whole face

Mesh, cobweb-like threads you will grow

Powdered with black dust and I know

You have roots and black balls with spores

In moist air you maintain your laws

Mildew you are a parasite

You feed on living things on site

You are sometimes seen powdery

You are sometimes seen as downy