Who laid eggs on my passion vine?

You have passion vine growing and notice eggs on the vine. You live in an area where you will see both Gulf Fritillary and Zebra Longwing butterflies flying about. Which one laid the eggs?

First, as a general rule, Gulf Fritillary butterflies prefer to lay eggs in bright sunlight, on plants growing in full sun. Zebra Longwing butterflies prefer to lay eggs in the shade, on plants growing in the shade. That being said, Zebra Longwing butterflies will lay eggs on plants growing in the sun on cloudy days.

Second, both lay eggs singly, one at a time. Why do we see eggs in clusters at times? Simple!

A cluster of Zebra Longwing eggs

Zebra Longwing butterflies lay eggs in the tip of new growth, one at a time. They are often in clusters because there are usually only a few ‘perfect spots’ that their instinct allows them to use. They also lay eggs on tendrils near the tip of the plant. It is fairly unusual to see their eggs on leaves unless those leaves are right at the tip of a vine.

Zebra Longwing eggs on a soft tender passion vine tendril.
This Zebra Longwing is laying eggs in captivity. Although the plant was large, their instinct demanded that they lay eggs on the tip and tendrils and they did so, rather than use any other part of the plant.

Gulf Fritillary butterflies are not so particular. They will lay eggs almost anywhere on or near the plant. They usually don’t lay on the freshest growth.

A Gulf Fritillary lays an egg on a tendril near the base of a passion vine plant
A Gulf Fritillary laid an egg on the post that is supporting a large passion vine plant

When they lay eggs off a plant, it wasn’t an accident. They lay eggs off the plant as often as on the plant. A blade of grass, a strand of Spanish moss, a post, even you are fair game if you are near the plant.

After laying an egg on the first finger,
this Gulf Fritillary proceeds to lay an egg on the second finger.
A Gulf Fritillary laid an egg on a wire that is supporting a passion vine growing in the sun.
While in the garden one day, I found two Gulf Fritillary chrysalises. One had died.
On it were two Gulf Fritillary eggs.

Of course, there are always exceptions. Be prepared for those that do not play by the rules.

Side note: freshly laid eggs of both species are yellow. As the caterpillar inside develops, the eggs turn a dark burnt orange color.

Gulf Fritillary eggs – the yellow one is freshly laid
and the orange one is about to hatch

Zebra Longwing caterpillars are dark when they first hatch, not totally white as they are once they begin to grow.

Freshly hatched Zebra Longwing caterpillars

Look closely at the image below. Do you see the clear egg shells? A predator, such as a tiny spider or a lacewing larva has drained the egg of its contents.

Empty egg shells were drained of their contents by a predator,
such as a spider or lacewing larva