The End Result of Butterfly Courtship

Paying attention to the world around you will help you develop the extraordinary capacity to look at mundane things and see the miraculous.

~Michael Mikalko

Last week I did a post on the courtship behavior and egg-laying by Falcate Orangetip butterflies in our yard. I watched a female lay two eggs on two different plants of Hairy Bittercress, a common yard weed in the mustard family.

Falcate orangetip egg

Falcate Orangetip egg laid on March 20 (click photos to enlarge)

Times being what they are, I figured I would dig up a couple of the plants that had eggs on them and bring them inside to observe. I have never found one of the incredible thorn-mimic chrysalids of this species (they are tiny and apparently really blend into branches and tree trunks), so I thought this might be my chance if I could keep these little guys alive long enough. Most butterfly eggs I have watched hatch in just a few days, so I was getting worried when a week had gone by and nothing had happened. Each morning I pulled the now potted weeds out of the butterfly cage and examined them with a hand lens to see if the egg had hatched. Finally, yesterday morning (March 30)…

hatched egg of falcate orangetip

The remnants of one of the butterfly eggs; the other egg was apparently totally eaten by the larva.

…both eggs had hatched – about 11 days after they were laid! The first plant had about half of the egg shell remaining. When I searched the other plant, there was no egg casing at all. That is pretty typical since many butterfly and moth hatchlings will eat their egg shell right after emerging.

Falcate orangetip larva first instar 2 days old

The tiny first instar larva of a Falcate Orangetip butterfly.

It took some searching with a magnifier to find each of the new larvae. They are only about 2 mm in length and have tiny hairs scattered on their body with what looks like a drop of liquid at the tip of each hair. This may be some sort of predator deterrent. I found both larvae feeding on a developing seed pod of their respective plants. With the month ahead being one of mainly home-bound observations, I’ll keep tabs on these guys and try to provide an occasional update on their progress and changes (because I know you just need to know:).

 

Butterfly Courtship

My scientific life has been spent describing the interactions that occur when butterflies meet and trying to understand what is going on and why…I persist in following butterflies with stopwatch and notepad.

~Ronald L. Rutowski, North American Butterfly Association

Yesterday’s sunshine (why can’t we seem to have at least two days in a row of that here lately?) brought out the invertebrates in the yard. I looked out the window at one point and saw a fluttering small white butterfly checking out the Hairy Bittercress weeds in the front yard. It was a female Falcate Orangetip (Anthocharis midea), and those weeds, members of the mustard family, are one of her host plants. These tiny butterflies are one of the sure signs of spring as they fly for only a couple of weeks early each year, looking for members of the mustard family on which to lay their eggs.

Hairy bittercress

The distinctive developing seed pods of the common yard weed, Hairy Bittercress, Cardamine hirsuta (click photos to enlarge)

I grabbed my camera and by the time I got outside I saw another butterfly, this one with orange wing tips (a male Falcate Orangetip), pursuing the female. What followed was 3 minutes of intense butterfly behavior (and burst mode shooting on my part). The male’s flight pattern was rapid and erratic and he would dive in and briefly flutter near her before darting off and circling back.

Falcate orangetip butterflies mating behavior 2

Male Falcate Orangetip (with orange wing tips) fluttering near female perched on one of her host plants.

Falcate orangetip butterflies mating behavior

The female maintained an abdomen up position the entire time.

Falcate orangetip butterflies mating behavior 1

It seems as though the male’s efforts were unsuccessful as he eventually flew off and she continued patrolling the yard for bittercress.

I have seen this abdomen up behavior before when watching Falcate Orangetips. I have always assumed it was the response of a female that is not interested in the male’s attention. But, some research on a closely related European species shows that both receptive virgin females and non-receptive, previously mated females, show this raised abdomen behavior when a courting male comes a calling. The difference may lie in what chemical compounds the female is releasing when the male gets close. In one case, it may be an attractant pheromone. In the already mated females, it is believed to be a repellent.

Falcate orangetip egg

A single tiny egg on the flower of the host plant.

After the male departed, I tried following the female around the yard to see if she was going to lay an egg, but she eventually wandered off through the woods. I went back to the original plant I had seen her land on and began to search it for an egg. I finally found one – a tiny sculpted egg, laid at the base of a flower, just where the online references had said it would be. She supposedly deposits a pheromone on the egg that keeps other females from laying an egg on that same plant as the larvae are known to be cannibalistic. Now I want to try keep track of it as the larvae (and especially the thorn-like chrysalis) are extremely hard to find. The things you can do in self-isolation…

For more on the behavior of butterflies and their mating habits, check out this article, When Butterflies Meet, from the North American Butterfly Association.