How many insects are there—and why do we need them?

There are an estimated 10 quintillion insects alive on Earth at any given time. That's 10,000,000,000,000,000,000 individual insects. But how many species are there, why do we need them, and what would happen if their numbers continued to fall? Dr. Alex Dittrich, a zoologist at Nottingham Trent University, explains why these small creatures play such a big role in keeping our planet functioning.

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