Butterfly dossiers

Twelve species, four families, one page of fields each. The grouping below is taxonomic rather than by habitat or colour, because the family is the fastest way to predict what a caterpillar will eat: swallowtails take umbellifers and trees, brush-footed species take nettles, milkweeds and thistles, whites take brassicas, and gossamer-wings take legumes and shrubs. If you know the family you already know half the plant list.

Swallowtails

2 dossiers

Large, tailed wings and an orange forked gland the caterpillars flick out when touched.

Black Swallowtail

Papilio polyxenes
- 6.9-8.4 cm
- Host: Dill, parsley, fennel, carrot, cel…
The black swallowtail is the swallowtail you can actually get without owning land. Its caterpillars eat dill, parsley,…
Eastern Tiger Swallowtail

Papilio glaucus
- 7.9-14.0 cm
- Host: Wild black cherry, tulip tree, gre…
The Eastern tiger swallowtail is the butterfly most people picture when they hear the word swallowtail: four inches of…

Brush-footed

2 dossiers

Brush-footed: the front pair of legs is reduced and hairy, and never used for walking.

Painted Lady

Vanessa cardui
- 4.8-6.5 cm
- Host: Thistles, mallows, hollyhock, comm…
The painted lady is the most widespread butterfly on earth, found on every continent except Antarctica. It cannot surv…
Monarch

Danaus plexippus
- 8.9-10.2 cm
- Host: Milkweeds - common milkweed, swamp…
The monarch is the only butterfly most people can identify from a moving car, and it is also the only one in North Ame…

Whites and yellows

1 dossier

Whites and yellows, mostly brassica or legume feeders, with the chrysalis held by a silk girdle.

Small White (Cabbage White)

Pieris rapae
- 4.5-5.5 cm
- Host: Cabbage, broccoli, kale, radish, n…
The small white is the most familiar butterfly in the world and the most disliked one. Its caterpillar is the green wo…

16 more dossiers are written and queued. They join the families above on their release dates, so the counts on this page will change from week to week.

Reading the fields

Wingspan is given as a range because males and females differ, and because the same species is smaller in the north of its range and larger in the south. Host plant is the plant the caterpillar will actually eat — a butterfly will often nectar at a plant its caterpillar cannot survive on, so the two lists are never interchangeable. Nectar plant is what the adult uses, and it is usually a much longer list than the host list, because adults are generalists and caterpillars are not. Life cycle is written as a one-line sequence from egg to adult with the overwintering stage named, since that is the single most useful thing to know when deciding what to leave standing in a garden over winter.