It's an eastern tailed blue. They're closely related to the hairstreaks, even rub their hindwings together in hairstreak style.
Congratulations to your daughter!

Sherry

Sherry,
What a thrill, thank you! Can you tell me what their host plants are? Trying to hook the kid on horticulture and the natural world...thinking she could grow some of their favorites... :-)

Eastern tailed blues are one of those little butterflies I've never raised, and I can't remember anybody on this forum ever posting about raising them. So, I looked up the info. All the books agree that they use various members of the legume family, and all the ones they list are low growing types, not trees, such as black locust. The best information comes from The Butterflies of West Virginia and Their Caterpillars by Thomas J. Allen -

"Females oviposit between the flower buds or on young leaves of the host plants usually during the afternoon. Eggs are laid singly and larvae feed primarily on the buds but will eat young leaves as well. They are attended by ants that seek their honeydew secretions. (snip) The caterpillar is variable but is usually green with pale green, oblique lateral stripes, a dark dorsal line, and a yellow sublateral line. It is covered with fine whitish hairs. The chrysalis is pale to dark green or brownish yellow and is also variable. Caterpillars hibernate, often in seed pods, and pupate in spring.

The eastern tailed-blue uses legumes as hosts. In West Virginia, bush clovers (Lespedeza spp.) are a favorite host as well as red clover (Trifolium pratense). They also use alfalfa (Medicago sativa) and rabbitfoot clover (T. arvense) on shael barren sites. Other legumes also reported include vetches (Vicia spp.), beggar's ticks (Desmodium spp.), and yellow sweet clover (Melilotus officinalis)."

You could buy some clover seeds of the above listed types and let your daughter sow them in her own garden. Only problem is, since nobody that I know of here has seen a cat or chrysalis, they might be hard to find, but it's worth a try.

If your daughter wants to get into butterfly gardening, something like fennel, dill, milkweeds, etc. that host more-commonly-raised-by-people types of butterflies might be a good choice.

I hope we have a budding gardener, maybe even a lepidopterist! :)

Sherry

The one ETB hostplant that always sticks in my mind is beggarweed. No clue what it is but I always remember the name.

Thanks everybody for your responses.
Our property abuts farmland; crops grown include soybeans so I suppose that's where many a young ETB gets its start. I keep an acre of our property unmowed for butterflies. Each year as my knowledge expands I add new plants to the meadow. We are seeing the results, some days are thick with butterflies, and I'm amazed at the diversity of the creatures we are able to attract! I have swaths of clover and many types of native grasses, as well as Desmodium canadense (commonly called Beggar's Ticks--I believe this could be what kcclark was referring to) so I have high hopes of seeing more of these delightful creatures. Thanks again for your help.
regards,
seedmoney

From the FAQ:

Eastern Tailed Blue
- clovers
1. Securigera (Coronilla) varia - crown vetch

Larry,
Thanks for bringing my attention to the FAQ--found many gems there. Am wondering if my ETB is male or female?