But, if there are only a few lichens in your neighborhood, the air you are breathing is probably clogged with automobile fumes or industrial wastes. Useful Lichens Lichens are important in many ways in the habitat. Some make the nitrogen in the air usable to plants, They are homes for spiders, mites, lice, and other insects. All are important in the nutrient cycle in the places where they grow. Humans have learned to use lichens in many useful ways.
Drug companies make antibiotics from lichen substances.
Lichens can also tell us if the air is clear and clean because many lichens die when the air gets polluted. One of the most creative things people do with lichens is make dyes to color wool. Below are some examples of wools dyed with lichens. Some colors are very subtle, while others are bright and cheerful. These pieces of wool were dyed with lichens.