It is common to see many different kinds of insects while spending time outside in the summer. Some of these tiny creatures do not bother people and can even add beauty to the natural environment. Examples of these are insects like ladybugs, butterflies and fireflies. Other insects can harm the environment or humans. Many are known to bite or sting. Some carry dangerous diseases. This group includes insects like mosquitoes, ticks and cockroaches. The population of these insects seems to stay large and healthy. But scientists say this does not appear to be true for some flying insects that serve an important purpose. There is growing evidence that these insects are decreasing across the world. Many of these insects are very important to plant growth and development. They also serve as a necessary link in the food chain and can help break down life when animals die.