Which of the following is not an insect?

• A. Mosquito
• B. Housefly
• C. Spider
• D. Butterfly

To determine which of the options is not an insect, we first need to understand the characteristics that define insects and how they differ from other arthropods, such as spiders. Insects belong to the class Insecta and have specific features that set them apart.

Characteristics of Insects

Insects typically possess the following traits:

• Three main body segments: These are the head, thorax, and abdomen.
• Six legs: All insects have three pairs of legs.
• Wings: Many insects have wings, although some do not.
• Exoskeleton: Insects have a hard outer structure made of chitin.

Examining the Options

Now, let’s look at each option:

• A. Mosquito: This is an insect. It has a segmented body, six legs, and typically has wings.
• B. Housefly: Another insect, the housefly also has the defining characteristics of insects.
• C. Spider: This is not an insect. Spiders belong to the class Arachnida, which is distinct from Insecta. They have eight legs and two body segments (the cephalothorax and abdomen).
• D. Butterfly: Butterflies are indeed insects, known for their colorful wings and metamorphosis.

Conclusion

Based on this analysis, the correct answer is C. Spider. While spiders and insects are both part of the arthropod phylum, they belong to different classes and have different anatomical features. Understanding these distinctions helps clarify the diversity within the animal kingdom.