Insects:
Insectclopedia
Insects - Environmental Education for Kids - EXCELLENT elementary level

Bees
Beekeeping: the beekeepers Home Pages - Beekeeping, honey, and honeybees are described in pictures and words. Designed for both children and adults. Includes links to hundreds of bee sites on the Web, some especially for kids.

Butterflies:
Children's Butterflies - USGS - very informative

Spiders
Spiders - Environmental Education for Kids - EXCELLENT

Worms
Worms - Environmental Education for Kids - EXCELLENT