Eggs in the Yard

Notice the small things. The rewards are inversely proportional.

~Liz Vassey

While sitting out in the yard last week, we noticed a butterfly flitting around a few plants at the edge of the woods, a flight pattern that usually indicates it is a female looking for a place to lay an egg. The butterfly was an Eastern tiger swallowtail, so we knew she was looking for either a tulip poplar or a wild cherry, the two common host plants in these woods. She finally landed on a tulip poplar leaf, paused for a couple of seconds, and flew off. Melissa ran over to look, and after searching for a minute, found an egg.

Eastern tiger swallowatil egg with finger for scale

Eastern tiger swallowtail egg (click photos to enlarge)

Finding butterfly eggs can be relatively easy if you find a female butterfly hovering near her host plants. They usually flit around, twisting and turning, as if searching for something (which they are). They may land on a leaf for a second, “tasting” the leaf with chemoreceptors in their “feet”, to see if this plant is the right one. If not, they move on. If it is, then she may curl her abdomen and linger for a second, attaching an egg in the process. The female secretes an adhesive substance to secure the egg to the leaf.

tiger swallowtail egg

Eastern tiger swallowtail egg on a tulip poplar leaf

Eastern tiger swallowtails lay a greenish egg that blends very well with the leaf surface, making it tough to spot. The past few days I searched a few more tulip poplar saplings at the edge of the yard and came up with a couple of more eggs.

Tulip poplar leaf with egg wide view

Can you see the swallowtail egg on this leaf?

¬†Hint…click on the image to enlarge…it is on the right side of the leaf.
Tiger swallowtail egg close up

Close up of Eastern tiger swallowtail egg

Swallowtail eggs are somewhat spherical, although the base is a bit flattened where it attaches to the leaf surface. Unlike many other butterfly eggs I have seen, swallowtail eggs lack ridges, spikes, or other sculptural elements that can give insect eggs such exquisite shapes. But, in their simplicity, they are both gorgeous and elegant.

tigr swallowtail first instar 1

First instar larva of Eastern tiger swallowtail (very recently hatched)

Large numbers of tiger swallowtails are flying this spring, so I would have expected to find even more eggs and larvae than we have. But, this forest is dominated by huge tulip poplars, so I imagine most of the egg-laying occurs high up in the canopy, far beyond the peering eyes of a couple of egg hunters. Over the past couple of days we did find a couple of recently hatched larvae down low, so I grabbed a few photos of these bird poop mimics.

Tiger swallowtail early instar 2

Early instar, “bird poop mimic”, of Eastern tiger swallowtail

bird poop

Real bird poop on a poplar leaf (probably don’t want to click on this photo)

I even found a couple of leaves with real bird poop, and I couldn’t resist sharing the similarity to our little caterpillars.

Tiger swallowtail early instar 1

Curled caterpillar looking like some bird poop. Note the silk pad the larva has created on the leaf for attachment.

The combination of a dark background color with a white patch on these larvae does make for a distasteful-looking  mimic.
tiger swallowtail third instar

Later instar (third?) of Eastern tiger swallowtail

Yesterday evening, we found where one of the dark bird poop mimics had already molted into a green version, suspended above the leaf surface on their characteristic silk pad. The larval stage of this species lasts about two weeks and they molt five times as they progress from newly hatched caterpillar to chrysalis.

zebra swallowtail egg

Zebra swallowtail egg on underside of pawpaw leaf

The yard has a variety of host plants for different species of butterflies and moths, so I decided to check for eggs of a couple of other swallowtail species. The small stand of pawpaw is usually good for a couple of larvae of the beautiful zebra swallowtail butterflies. This species lays its eggs on the underside of the leaves, so I started searching and eventually found a few eggs. They are white to cream-colored, and usually placed near the edge of the leaf, which makes sense, since the female lands on top of the leaf and then curls her abdomen underneath to lay the egg

zebra swallowtil first instar wide view

Freshly hatched larva of zebra swallowtail (which dark spot is the caterpillar?)

Yesterday, I again looked for the eggs and found freshly hatched larvae, the smallest ones I have ever seen. Zebra swallowtail larvae are black in the first couple of instars.

Zebra swallowtil first instar

First instar (recent hatch) of zebra swallowtail

A closer view shows they lack a large white patch so common in the other larvae that mimic bird droppings.

Spicebush swalloewtail egg laid same day

Spicebush swallowtail egg on the underside of a spicebush leaf

As luck would have it, while eating lunch yesterday, I saw a dark swallowtail hovering around plants, obviously looking for that special place to deposit an egg. She eventually made her way to an isolated spicebush shrub, and began laying. She flitted from one leaf to another, eventually laying three eggs on that shrub, one each on the underside of three different leaves. These eggs look similar to those of the zebra swallowtail, although perhaps a tiny bit larger.

I checked my parsley and fennel leaves in the garden, but no signs yet of black swallowtail eggs, so I will have to be content with three species of swallowtails for the time being. Still, this is a great start to my favorite time of the year – caterpillar season. It reminded me of a post I did last summer after finding three species of swallowtail caterpillars in one day. But I’ll keep looking at the parsley and the pipevine to see if I can break that record and maybe get to a five cat day this year.





Three Cat Day

Nature is to be found in her entirety nowhere more than in her smallest creatures.
~Pliny the Elder (Roman scholar)

When visiting Yellowstone, it is a great thing when you have a “three dog day”. That refers to a day where you are lucky enough to see the three primary species of canids found in the park – a Red Fox, a Coyote, and a Gray Wolf. Yesterday, in my yard, I had a different type of triple sighting, but I’m not quite sure what to call it. I am definitely in late summer mode, which means caterpillars on the brain, an annual disease that afflicts people like me and anyone else working the BugFest caterpillar tent. So, starting about now, anytime I take a walk outside, my eyes seem to be constantly scanning the vegetation for Lepidoptera larvae.

Eastern Tiger Swallowtail black phase female

Eastern Tiger Swallowtail, black phase female (click photos to enlarge)

There have been large numbers of Eastern Tiger Swallowtail butterflies in the yard the past several weeks. This phenomenon occurs every few years when some unknown (to me anyway) set of environmental conditions are right – the flowers are crowded with bold yellow and black-striped butterflies. There are also a lot of black-colored swallowtails mixed in, representing a few common species – Spicebush Swallowtails, Black Swallowtails, and the occasional Pipevine Swallowtail. And there is one other – female Eastern Tiger Swallowtails can either be the familiar yellow color with black stripes, or they can be a darker morph, appearing black, or black with a hint of yellow.

Eastern Tiger Swallowtail larva

Eastern Tiger Swallowtail larva

So, with all this recent swallowtail activity, my first stop on the caterpillar hunt was a grouping of sapling Tulip Poplars, a primary host plant for Eastern Tiger Swallowtails. After scanning a few, I finally spotted a larvae on the surface of one of the large leaves, resting in a silk pad. This is typical behavior for this species. And, like most of its swallowtail family, the earlier instar larvae resemble bird poop. Guess it is a great strategy to avoid being eaten by foraging birds – look like something they have already eaten and processed. The larvae of this species will eventually turn all green (with small fake eye spots) as it molts and matures.

Black Swallowtail caterpillar last instar

Black Swallowtail caterpillar, last instar

Continuing my stroll, I caught the unmistakable black and yellow pattern of another member of the swallowtail group (family Papilionidae) tucked under some Parsley leaves. Black Swallowtail larvae also start out as bird poop mimics, but this one was in its last instar and had outgrown that unsavory likeness.

Spicebush Swallowtail folded leaf

Folded leaf on a Spicebush, Lindera benzoin

The next stop was a semi-bog garden. There are chances here for two additional species of swallowtail larvae – Spicebush Swallowtails on the Spicebush, and Zebra Swallowtails on the Pawpaw. There were several folded leaves on the Spicebush, the telltale sign of caterpillar activity.

Spicebush Swallowtail larva late instar

Spicebush Swallowtail larva, late instar

I carefully unfolded one leaf and found a comical-looking Spicebush Swallowtail caterpillar. These little guys are one of my favorites, with their large, detailed fake eye spots giving them a bit more personality than most larvae. All stages of the larvae of this species spin silk across a leaf causing the leaf to gradually fold over as the silk dries and contracts.

Spicebush Swallowtail larva first instar

Spicebush Swallowtail larva, first instar

It makes a good hideout and probably provides some protection from the many predators out there, especially the hungry birds and paper wasps (wasps cut up caterpillars and feed them to their larvae in the nest). But it also makes them easy to find for us caterpillarophiles.

Spicebush Swallowtail larva

Spicebush Swallowtail larva, bird poop mimic

There were a lot of folded leaves on the plants, especially one near the house I had trimmed that had re-sprouted. I think these fresh leaves are perhaps more palatable for the larvae and therefore more sought out by egg-laying female butterflies. One sprouting plant had what appeared to be all stages of development of the Spicebush Swallowtail larvae (another bird poop mimic in its first three instars).

I tried in vain to find a Zebra Swallowtail caterpillar on the Pawpaw (its host plant), but I have always found them to be one of the more difficult larvae to locate. But, three swallowtail species in one afternoon – not bad. A three cat day? Three cat-tail day? Whatever it should be called, it is a good thing.