The Giant Swallowtail butterfly

The Giant Swallowtail (Papilio cresphontes or Heraclides cresphontes) is a truly spectacular butterfly in the Parnassian (Papilionidae) family of butterflies. The upper-side is dark with a yellow chevron and the under-side is the yellow that just can't be described. It is a fairly large butterfly whose wingspan can reach from 4" to 6.25" and when you see one, you won't likely forget it!

Even a tattered and torn one, as the one pictured on the title of this blog is still a beauty. The Giant Swallowtail (name shortened to GST) is generally found from May through September in many parts of the United States but flutters about year-round in Florida and in the south.

If you happen to have citrus trees and have found a 'scary' looking worm-like creature on the leaves of your trees, then you may have found a GST baby! The larvae of the Giant Swallowtail actually resembles bird poop which is a great form of camouflage as it helps to keep the birds and other predators from eating them.

They also have an interesting body part that, if provoked, will 'come out' like big reddish-orange antlers along with a most detestable odour (reminds me of a stinky cat litter box!). The osmeterium will then go right back and the caterpillar will continue doing whatever it was doing (probably eating) now that the predator has been properly chastened.

The Giant Swallowtail will oviposit (lay eggs) on trees and herbs in the citrus (Rutaceae) family such as Navel orange, Rue (Ruta graveolens), and Meyer's lemon; and Hop tree (Ptelea trifoliata).

The mama butterfly will often look for a young leaf and will oviposit singularly on the top of the leaf. Keep in mind, that this is not always the case as I have found eggs on older leaves and even on the undersides of a few...

Here is a picture of Rue with some of its pretty yellow blossoms.

GST eggs are spherical as are many of the butterfly eggs of those in the swallowtail family.

The GST egg pictured is on the end and on top of a Rue leaf.

After five days or so, a little Giant Swallowtail caterpillar hatches from the egg.

First, you will see its little head poking through the eggshell.

It will then slowly work its way out of its shell, twisting and turning until it can get out.

It will turn around and eat its eggshell then begin to eat the leaf upon which it was laid. The hatchling is usually more brown and tan in colour and changes to the darker gray in a later instar. Even at the 1st instar, when provoked, the larva will 'shoot out' its osmeterium! Check it out here; you can see it if you look carefully!If anything bad is going to happen, it is probably going to happen when the little one is tiny (1st or 2nd instar). These little guys are most delicate when they first hatch. Why? I don't know. Less handling is best.This little hatchling (1st instar) is on an orange leaf. Note the light-brown coloration.

Here is a 2nd instar. It still looks a lot like the 1st instar. The front part is beginning to thicken (towards the head).

If raising GSTs be aware that the larvae (caterpillars) are most definitely cannibalistic. What?! Yes, they can (and most likely will) eat one another if raised in the same rearing container. I learned this lesson after raising a number of Giant Swallowtails in small containers and found that I was suddenly 'missing' one and another was quite large in size one day. This seems to occur once the larvae get to be about 1" least in my experience! Now I am more careful and do not keep all siblings in the same container.

GSTs do not move very quickly. They often will eat then remain still for long periods of time. They don't seem to indulge in as many leaves as other butterfly larvae. They are considered a pest, however, and are often called 'Orange Dogs' by those who work in nurseries.

Interestingly, I have found that there are some people who work in nurseries who did not realize that the 'Orange Dog' actually was the larvae of the Giant Swallowtail butterfly! They just thought it was a terrible pest that must be eradicated. (No wonder when I'd come along and offer to take the little guys off of their citrus plants they would be quite happy!)

If you were to touch the GST caterpillar, you'd find its skin to be smooth...somewhat similar to that of a Gummi Worm. Ahhh...

When it is time to pupate, the GST will look for a place on which to make its sling. Like other swallowtails, the GST does not hang upside-down and form a 'J' but will make a silken harness and hang at a diagonal, right-side up. The pupa is sort of a brown and if you look at it carefully, it just might remind you of a character from Disney's Alice in Wonderland!

Now, here's an interesting thing about swallowtails. You just can't be on a time schedule with them when you want them to eclose. Just because you have a pupa or two or three, don't expect them to eclose so that you'll have butterflies fluttering about in two weeks. Giant Swallowtails overwinter as pupae and IF they don't want to eclose right away, they just won't. I've had some that decided to 'hang around' for ten months or so then one day, just eclosed.

Enjoy raising these beauties. When they are young, they are tender little things. When they are grown, they are truly spectacular.

Special note: If you want to gender ID male/female adult Giant Swallowtails, look at the end of the abdomens. Males have 'claspers' and they are quite obvious to see! (All male butterflies have claspers but they are more easily seen on the GST.) Click on the picture on the right to enlarge it. Now, click on the picture of the butterfly on the above left. You will note that the female does not have the claspers!