These types of beetles are often referred to as lightening bugs. They are one of the most popular bugs due to the light they give off in the dark. Very little heat is radiated from this light so it requires little energy to produce. The light is used quite simply to attract their mate.
While many types of beetles are considered pests, causing harm sometimes to crops and infesting food, beetles are very beneficial. They play a very important role in returning organic matter to contribute to soil fertility.