I have a bright yellow foamy substance in a house plant? What could this be?

Question

The bright yellow substance looks somewhat like pieces of styrofoam lying on the surface of the soil. I scooped it out one day but there was even more of it two or three days later. I thought it was a fungus, then I found a bug that looked like a large black ant digging around the top of the soil of another plant.

Answer 1

Your first guess was likely right.  Sounds like Dog Vomit Slime Mold.  Sounds disgusting, but ants and other insects (especially beetles) eat it.

See the second item on this page:

http://botit.botany.wisc.edu/toms_fungi/...