The excretion in insects is by ………. .

Explanation

**Step-by-Step Solution:**

1. **Identify the Excretory Organ in Insects**: Insects have a specialized organ for excretion, which is crucial for removing waste materials from their bodies.

2. **Name the Organ**: The organ responsible for excretion in insects is called the Malpighian tubule.

3. **Function of Malpighian Tubules**: The Malpighian tubules function similarly to kidneys in vertebrates. They collect waste materials from the hemolymph (the insect equivalent of blood) and facilitate their excretion.

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