Celastrina neglecta, the summer azure, is a butterfly of the family Lycaenidae.

Layberry, Hall, and Lafontaine, in The Butterflies of Canada, describe the species: The upper surface is pale blue with an extensive dusting of white scales, especially on the hindwing.

Known host plants for the caterpillars include New Jersey tea, dogwoods, and meadowsweet.

Adults nectar from many plants including vetch, yarrow, meadowsweet, rough-fruited cinquefoil, Queen Anne's lace, wild oregano (Origanum vulgare), narrow-leaved mountain mint, Joe-pye weed, and goldenrods.

[3] The taxonomic status of this butterfly, originally described as Lycaena neglecta Edwards, 1862, has been in flux over the years.