I found a yellow caterpillar of the Cloudless Sulphur Butterfly (Phoebis sennae) on my Partridge Pea (Chamaecrista fasciculata). I was happy because I do a feature in the monthly issue of The Lily Pad, a newsletter that I write for The Florida Native Plant Society-Osceola County local chapter. The feature is called Before and After, where I feature an insect photographed in it’s larval state and then as emerged in adulthood. I was running out of “befores”.
While eating flower buds, a lovely shade of yellow
I photographed my find and headed in to make sure I had identified it correctly. Now mind you, it was the third new-to-me caterpillar I found this week, one being an armyworm and the other, some sort of Owlet Moth (Noctuidae) larvae. I am still having a hard time pinpointing the owlet species and I’m sorry that I didn’t collect it when I had the chance. By the time I got back to it, it was long gone.
My Sulphur caterpillar looked similar to others posted at bugguide.net. But some were a horse…ummm…cat of a different color. Insect ID’s aren’t always as simple as one might think. I checked a few different Websites with photos and read, with interest, anecdotal information that caterpillars may change colors based on the part of the plant that they eat. I found another site that specifically mentioned sulphur caterpillars as doing this. When they dine on the flowers, they are yellow, but if they switch to the leaves, after the flowers are spent, well, they turn green. THIS I HAVE TO SEE WITH MY OWN EYES!
Left with only leaves to eat, my caterpillar friend turns green
I have often said that I only capture critters when it involves educational study that does no harm, and I felt that this qualifies. I immediately gathered the little yellow cat and a branch of the plant and placed them in a roomy display case (relative to the size of the cat). It was munching away on the flower. I added a small paper towel square dipped in water to maintain moisture and placed the container where it would get brief morning sun, but not so much as to fry the poor thing. The next morning I checked on my guest and (s)he was now munching away on the leaves, and was beginning to look a little “green”. I went out and got a fresh branch of the plant…who likes eating day old food? My charge dutifully climbed onto the fresh greens and I replaced the screening and rewet the paper towel square.
Day four even greener
Day four, I checked again, and (s)he is even more vivid green. To me this is an interesting phenomenon. There are a lot of caterpillars that are “generalists”— that is, they eat more than one species of plant and I guess they would have color variations based on what plant they choose. An “aha” moment in my occasional problem with identifying cats. Here is verbiage from across the pond:
”With each successive moult, the caterpillar changes it’s appearance, both physically, and in colour and pattern. In some species, such as Satyrine butterflies, the changes are minimal – often just a slight change in colour so that the younger caterpillars match the shade of the fresh young leaves on which they feed, while the fully grown larvae become darker, matching the colour of old leaves.” [Source]
Early Instar of Banded Sphinx Moth Caterpillar (Eumorpha fasciatus)
Other reasons for color variations may include: a change in the color of a plant (how they blend in to avoid predation or crypsis), the area of the country they are from, the time of year and the stage of development (what instar they have reached).
Later instar of Banded Sphinx has quite a different color scheme
Have you noticed this in your own wildlife garden?
A research hypothesis on plant coloration from Harvard Forest (Harvard University) was used as a source of some information in this article.
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About Loret T. Setters
How wonderful to witness this. I have found the frogs will do this in my pond from time to time as well..
Donna@Gardens Eye View recently posted..Leaving the Nest
Interesting that you say that Donna. I was having a tough time IDing a frog (which was actually a toad) hanging out in the pond during tadpole season. Eventually told it was a southern toad, most I had seen were a different color variation but were located up on my patio. You have now educated me that the color probably was because of the different areas of the yard …to blend in. Thanks!
Loret recently posted..My threatened species….REALLY?
The only colour changing I have seen is the flower/crab spiders. Pink white or yellow depending on the flower they call home.
Elephant’s Eye recently posted..Sunshine bush after the fire
Spiders too? Interesting! Thanks for sharing that. Now I will have to pay closer attention!
Loret recently posted..My threatened species….REALLY?
How interesting! It certainly makes the ID’ing of caterpillars even more difficult knowing that even a single species can be a range of colors…I understand that the color of the tip of cedar waxwing bird tails have changed over the last half-century from yellow to orange-red due to a diet shift to the invasive non-native honeysuckle berries – they pick up a pigment from the berries which appears in their tail feathers.
Ellen Sousa recently posted..The Year I Shall Win the Pachysandra War
I’m going to have to share that with my birder friend~~She gets the cedar waxwings in her yard when they come to florida to winter over. I’m going to have to get her to photograph their tails since I’m not lucky enough that they come to my little bit of paradise. Nature sure has some pretty interesting ways of contributing to a color pallette!
Loret recently posted..The Sulphur Butterfly Emerged Already!