Phoebis sennae

We don't have an image of P. agarithe for reference

but both Phoebis sennae and Phoebis philea have yellow forms that are somewhat similar to this. P. sennae seems more likely, especially given your location, though this doesn't have the bluish tinge to the stripes I've usually seen on that one. Any chance you could raise it to adulthood for a positive ID?

According to Minno's book(1) (which unfortunately only depicts the green form) the Phoebis agarithe caterpillars lack even the short spines seen on this one, so I don't think that's a likely ID.

… Hannah Nendick-Mason, 6 October, 2006 - 10:51am

I found one

and brought it home to try and raise to adulthood. Unfortunately I found one smaller than my originals, so it still has some growing to do. I hope I can keep the flower spike alive while it eats! I have a native Senna out in my flowerbed, so maybe it will feed on that if I need to get it something else.

… Aaron Goodwin, 6 October, 2006 - 8:59pm

Good luck

and if you can get measurements and a series of images as it grows, that will also be a good addition to the guide. It should switch OK to another Senna, especially if you can provide a flowering stalk. Unfortunately the flowers are harder to keep alive than leaves - you could also try leaves, as the caterpillar may be willing to switch - of course, it might also change color to a green form, depending how close to pupation it is.

… Hannah Nendick-Mason, 7 October, 2006 - 8:19am

...

The photos I saw of P. agarithe on the Web were pretty much inconclusive, so that's why it was just a guess. The hard part about some of these caterpillars is the fact that many have multiple forms. I'll see if I can find one again and raise it to adulthood. I figure they're very close to that stage now so it won't be too hard to do. Thanks, Hannah!

… Aaron Goodwin, 6 October, 2006 - 11:00am