Gotta Learn Them All!
The above pokemon are Caterpie, Metapod, and Butterfree; three of the first bug pokemon ever introduced. Caterpie is based off of Papilio glaucus larvae and has an osmeterium, an smell-producing organ that helps ward off predators by releasing a putrid scent. While the primary instars of the Papilio glaucus species are all brown in coloration, the fourth can be green. Caterpie's design is based off of this stage in development. As butterflies and their larvae have relatively short life-spans, Caterpie and its future stage, Metapod, only exist briefly before they "evolve" to the next stage.
Metapod is a sterotypical depiction of a chrysalis. As the middle stage of a complete metamorphosis, Metapod's name is derived from two words: metamorphosis and pod (genius, right?). As chrysalae are immobile and largely rely on defense in order to survive, Metapod has abysmal attack and relatively high defense. As the chrysalis stage is a relatively short part in the butterfly's lifecycle, Metapod does not stay in this stage for very long, evolving just three levels later.
Butterfree is the final stage of this evolutionary line and the final stage in Caterpie's metamorphosis. Being the butterfly pokemon, Butterfree's name is derived from butterfly and free. Appearance-wise, it is similar to the species Aporia crataegi in that its wings are white with black veining running throughout them. Butterfree's eyes are compound eyes (coincidentally, that is also one of Butterfree's abilities) in that they are massive organs constructed of many ommatidia, a sub-unit of the eye. This allows the insect to have a better field of vision. This is advantageous in a predatory situation.
As there is a complete change in bodily structure throughout this evolutionary line, this line is holometabolous. The immature Caterpie does not have wings or structures that are present in Butterfree, the adult stage. This evolutionary line is inconsistent as Caterpie is representative of a swallowtail butterfly larva and Butterfree is representative of a black-veined white butterfly.
Artwork: Ken Sugimori, 1995
The above pokemon are a series of bagworms, of the family Psychidae, and consist of a larval stage and both a male and female form.
Burmy, the larval stage in this chain, is representative of most bagworm larvae. Typically, the larvae of bagworms construct cases out of surrounding natural materials for protection, as is the case with Burmy. These worms are, in fact, not worms but caterpillars for a species of moth. As such, bagworms are herbivores and will eventually pupate. Burmy's name is a combination of the words "bag" and "worm".
The Burmy "evolutionary" line is unique in that it delineates depending on gender, as is the case with some species of bagworms. Due to sexual dimorphism, some species of adult female bagworms do not have wings, as is the case with the female evolved form of Burmy, Wormadam. Continuing with the bagworm theme, Wormadam's design is an insect surrounded by material from the surrounding environment. The encasing of Wormadam is dependent on the environment in which Burmy evolves in: sandy in dessert conditions, metallic in urban conditions, and verdant in floral conditions. While this component does not directly relate to the bagworm species, it does continue the allusion to bagworm cases formed from the environment. The name "Wormadam" is a combination of "worm" and "madam", continuing the female bagworm theme.
The male form of Burmy's evolution is Mothim, a bagworm moth. As previously stated, the sexual dimorphism of some bagworms makes it so that males undergo a complete metamorphosis (holometabolous) and develop functional wings. The name Mothim is a combination of "moth" and "him", continuing the theme of sexual dimorphism.
Art: Ken Sugimori 2006
Burmy, the larval stage in this chain, is representative of most bagworm larvae. Typically, the larvae of bagworms construct cases out of surrounding natural materials for protection, as is the case with Burmy. These worms are, in fact, not worms but caterpillars for a species of moth. As such, bagworms are herbivores and will eventually pupate. Burmy's name is a combination of the words "bag" and "worm".
The Burmy "evolutionary" line is unique in that it delineates depending on gender, as is the case with some species of bagworms. Due to sexual dimorphism, some species of adult female bagworms do not have wings, as is the case with the female evolved form of Burmy, Wormadam. Continuing with the bagworm theme, Wormadam's design is an insect surrounded by material from the surrounding environment. The encasing of Wormadam is dependent on the environment in which Burmy evolves in: sandy in dessert conditions, metallic in urban conditions, and verdant in floral conditions. While this component does not directly relate to the bagworm species, it does continue the allusion to bagworm cases formed from the environment. The name "Wormadam" is a combination of "worm" and "madam", continuing the female bagworm theme.
The male form of Burmy's evolution is Mothim, a bagworm moth. As previously stated, the sexual dimorphism of some bagworms makes it so that males undergo a complete metamorphosis (holometabolous) and develop functional wings. The name Mothim is a combination of "moth" and "him", continuing the theme of sexual dimorphism.
Art: Ken Sugimori 2006