Houseplants suffer from the stale, dry air in our winter homes, but more than that they suffer from overwatering.
Seeing little black flying bugs in and around house plants is a sign that the plant's soil needs to dry out more between waterings. The bugs are harmless to the plants but helpful to let you know when to cut back on water.
Running a small house fan close to plants in the house can help them, too. The air circulation helps strengthen the stems. Also, when watering house plants dump out any water that remains in the saucer. If you have ferns and think they need humidity, fill a shallow pan with stones and put the pots on top of the stones. Keep the water below the level of the top of the stones.
And then there are the small, yellow mushrooms in houseplants. They are the reproductive structure of a soil fungus. Also harmless to plants but poisonous to people and animals, so just to be on the safe side, remove them and dispose of them.