Entomology is the branch of science that studies insects. Insects are small creatures with six legs, like ants, bees, butterflies, and beetles.

Worms are studied under a different branch called helminthology or invertebrate zoology. Animals, in general, are studied in zoology, which covers all kinds of animals.

Entomology focuses on the life, behavior, ecology, and classification of insects. Insects are important because they affect agriculture, spread diseases, pollinate plants, and form part of the food chain.

So, the correct answer is insects.