Gulf Fritillary on passion vine (photo by Edward Rooks via Wikimedia Commons)
We normally see butterflies visiting flowers but they also flit from leaf to leaf.
Adult butterflies are on a mission to reproduce. Yes, they sip flower nectar along the way, but the males are looking for females and the females are looking for host plants on which to lay their eggs. When the eggs hatch, the larvae will eat the host leaves and grow into ever-larger caterpillars.
Each species has one or more hosts for their larvae. Monarch caterpillars eat milkweed leaves. Red Admirals eat nettle. Gulf Fritillaries eat passionflower vine.
Butterflies taste with their feet, so when the female is ready to lay an egg she flits from leaf to leaf landing on each one to taste it. Standing there she asks herself, “Does this taste good?” If so, she lays an egg.
Sometimes butterflies are fooled. To a West Virginia White butterfly (Pieris virginiensis) the invasive alien garlic mustard tastes like her host plant toothwort so she lays her eggs on garlic mustard and her hatchlings die of starvation.
Tastes can be pretty subtle, too. Monica Miller (my go-to butterfly expert) told me that if a food plant touches a nearby leaf, that leaf might taste good enough to be mistaken by a butterfly.
Here, a female Gulf Fritillary lands on her host plant (tasting it) and a male comes to court her.
Gulf Fritillary courtship on passion vine (photo by Edward Rooks via Wikimedia Commons)
And here’s her goal: She laid an egg on the passion vine.
Gulf Fritillary butterfly egg on passion vine leaf (photo by Edward Rooks via Wikimedia Commons)
Watch butterflies taste with their feet and you may see one lay an egg.
(photos by Edward Rooks via Wikimedia Commons. Click on each image to see its original)