Pollination

• Perhaps the most important role that insects play for plants is helping them reproduce. Plants have male and female sexual organs -- sometimes in the same flower, other times on different plants. The male parts, the pistils, produce pollen that must be deposited in the female part, the anther, so that a seed can form, which will hopefully grow into a new plant. Plants produce nectar to attract insects into their flowers, where the anthers and pistils are located. The insects brush against these as they feed, picking up and depositing pollen as they go.
  
  

Predation

• Some insects eat plants. Fortunately for the plants, other insects help protect them by preying on their herbivorous cousins. An apposite example of this is how some farmers and gardeners introduce ladybugs onto their plants to combat the destructive influence of aphids. Of course, some plants such as the Venus flytrap also eat insects.
  
  

Aeration

• Insects also burrow through the soil. This helps ensure that the soil does not become too compact, allowing water to flow through it and be made available to plant roots, as well as preventing the ground from becoming waterlogged. Waterlogging restricts the amount of oxygen in the soil while raising the amount of carbon dioxide, which can inhibit growth.
  
  

Decomposition

• Insects often feed on dead plant matter and animals that are on the ground. By doing so, they recycle the nutrients and chemical compounds within this organic matter, which, when it passes through them, becomes part of the soil and is made available to the living plants rooted within it.