Subject: Swallowtail Caterpillar(s?)
Location: Central Oahu, Hawaii
May 21, 2013 7:33 pm
I’ve had a fairly sizable giant swallowtail caterpillar living on my lime tree — I identified it based on the fact that it looked like a bird poo, as well as the little orange antenna-things and the bad smell when it’s alarmed. Two days ago I went outside to see how my little caterpillar friend was doing, and was surprised to find that, while he still had the same basic pattern on his body, it had all taken on a distinctly green hue. (Sadly, I did not get a picture.) Today I went out to check on him again, and found the fat green caterpillar in the second photo in the same general area I was used to finding my mottled friend. It’s definitely a swallowtail too.
My question is: Is this one caterpillar or two? Are giant swallowtail caterpillars known to change their colors and markings? Or is this a different breed and I was just supremely unobservant in not noticing it, again, in the same area as the ”other” one?
Many Caterpillars change their coloration and markings as they molt and grow through the various instar stages. We found a photo in our archive that matches your green Chinese Swallowtail Caterpillar, Papilio xuthus, a species that feeds on citrus. We learned on the Butterfly Society of Hawaii website that it is the only Swallowtail species documented in Hawaii. Softpedia has a photo of the different instars of the Chinese Swallowtail Caterpillar that resembles the photos of the two instars you have submitted. The same photo can be found on the Insect Hormones page where it is stated: “The swallowtail butterfly, Papilio xuthus, passes through 5 larval stages (“instars”) growing larger after each molt. The first four larval stages resemble bird droppings looking like brown fecal matter with a whitish paste of uric acid (which is the nitrogenous waste of birds). The photograph shows the 3rd (left), 4th (middle), and 5th (right) instars. See how after the fourth molt, the 5th instar has quite a different appearance — being well camouflaged as it feeds on its host plant (right).” While we cannot say for certain that these two are the same individual, we can say that they belong to the same species.
A Reader Comments: October 12, 2014
Thanks for the info. We have been noticing huge butterflies ?? in my back yard. So far, none have landed. My Lemon tree is fully infested with brown and ivory caterpillars of every size. I thought at first it was bird poop, but in looking at them with a magnifying glass and then coming to your web site, they are identified. as Giant Swallowtail butterflies. Their faces do look like Chinese Dragon Caterpillars on some of China’s decorative buildings. Also they are mimicked in the Chinese parade festivities.
How they came to Northwest Arizona in the 85388 area is a mystery. I have lived in Arizona 31 years, have always had citrus trees and never saw these until this year. They literally chew up all the leaves on all my citrus trees. Lemon trees affected the most. There are a lot of lemons on that tree and I don’t know if the lemons will be edible when they mature.Do they bore into the lemons and fruit? If they have not invaded Arizona, they certainly have invaded my yard and Citrus trees. (Newly landscaped yard in Dec.2013 when
Citrus Trees and other plants were planted.) 2 Trees, orange and grapefruit are struggling and growth stunted, while the Lemon tree leaves are being chewed away by the Chinese Swallowtail caterpillars.
In Arizona, they are most likely Giant Swallowtails and the Caterpillars are called Orange Dogs. Giant Swallowtails are native to eastern North America, but the introduction of citrus in Florida provided them with a new source of food. The cultivation of citrus in the southwest is a contributing factor to the increased range of Giant Swallowtails.