powdered oakblue (butterfly)
Refers specifically to the butterfly species Narathura bazalus. In everyday contexts, the katakana name is used.
I found a powdered oakblue in the garden.
purple martin (bird)
Refers to the bird species Progne subis. This sense is less common and may be encountered in ornithological contexts.
The purple martin is a migratory bird found in North America.
Katakana spelling is standard for this butterfly species name; usually written in kana.
Kanji form is rare and may be encountered in older or specialized texts; the katakana form is strongly preferred.
Compound of 紫 (murasaki, 'purple') and 燕 (tsubame, 'swallow'), referring to the purplish swallow-like appearance of both the butterfly and the bird.