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Insects in ecosystems

Insects in ecosystems: the many roles insects play. Pollinators (bees, butterflies, hoverflies), decomposers (dung beetles, fly larvae), food source for birds, bats, fish, and frogs, and pest controllers (ladybirds eating aphids). The thought experiment: what would happen if all insects disappeared?

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What a learner can do afterwards

  • Name at least three different ecological roles that insects play such as pollinator, decomposer, and food source
  • Explain how the removal of one insect group like bees would affect plants, other animals, and humans
  • Describe a specific example of insects as pest controllers such as ladybirds controlling aphid populations

The lesson

You already know insects sit near the bottom of food chains and that bees carry pollen between flowers. But insects do even more than that. Every day, insects pollinate plants, break down dead things, feed other animals, and even protect crops from pests.

dead leaffly larvaenutrientssoilnew plant
Fly larvae and dung beetles are decomposers. They break down dead leaves and waste, and the nutrients go back into the soil to feed new plants.
Try it together

Insects also work as pest controllers. A rose bush can end up covered in aphids, tiny bugs that damage the plant. Ladybirds eat aphids, and a few ladybirds can bring a big aphid problem back under control without any chemicals.

Beforeladybirds30Afterladybirds8

Now imagine every insect on Earth vanished overnight. Flowers would not get pollinated, so plants would make far less fruit and fewer seeds. Birds, bats, fish, and frogs would lose a major food source. Dead plants and waste would pile up with no decomposers to break them down. Aphids and other pests would spread across crops with no ladybirds to stop them, so people would lose food too.

Good to know

Next time you spot an insect, think about its job. It might be pollinating a flower, recycling waste, feeding a bird, or protecting a crop from pests.

Insects pollinate, decompose, feed other animals, and control pests, so losing them would break many parts of nature at once.

Watch it

Where it sits

Where this leads

Jobs that lean on this skill. Follow one to see everything it is built on.

Then practise

8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.

Insects in ecosystems · Science, ages 9 to 11 · LightMySky