Keys to adults, pupae, and larvae of seven common lady beetle species. There are very few resources, in print or online, with larval keys, and I've never seen a pupal key before. Though limited in scope, it can be used to ID the most commonly-encountered species at all life stages.

Species list:
Adalia bipunctata, two-spotted lady beetle
Coleomegilla maculata, (pink) spotted lady beetle
Coccinella septempunctata, seven-spotted lady beetle
Cycloneda munda, polished lady beetle
Harmonia axyridis, multicolored Asian lady beetle
Hippodamia convergens, convergent lady beetle
Hippodamia tredecimpunctata, thirteen-spotted lady beetle