I'm rearing Phoebis sennae - any tips?

As said they are very easy to rear either outdoors or indoors. If you have pointed questions it would maybe be easier to offer you something.

They can certainly be sleeved outdoors, but you can also have total control over them indoors, actually accellerate their growth with a rearing cage that you can control all of the normal environmental factors in. I built all my own cages, dozens of them in variuos sizes. But then I reared thousands of leps a year and that justified it. Not expensive to do if you have the tools and are handy. Having full control over photoperiod, temperature, humidity and air flow is ideal... I went a step further making my cages also water cages for the larval food plant cuttings to always be fresh yet provided for total drown ing safety for the larva. Even when I lived in the deep snow country of the frozen north I reared some species year-round with those cages, species from the America's and many other countries. Unfortunately I do not have pictures or drawings of the cages I designed to share. I used them for about 4 decades, they are still going strong for those I gave them to though. Anyway, even if you only increase the photoperiod it will accelerate their growth simply because they will eat more hours per day. Easy to do indoors with a light on a timer. Means replacing the plant more often if they are cuttings to keep it fresh though as the light will dry it out faster. I eliominated that in my cages by making them water cages with the side benefit of humidity control. Anyway, bBesides bacterial or viral infection, another possibility for the slows... their larva tend to be specific feeders in the broods active when the larval food plant is in bloom... some prefer the foilage, some the flowers and some will eat both. No idea where you are or if your senna is in bloom now, but if it is and you are not providing both it may be slowing some of them down.
FWIW


Where I live Senna armata grows wild in some places on the surrounding desert, and there are several ornimental senna's planted in town landscapes (lots of them in the association I live in). Some years the Pieriids that use it oviposit on those in front of my place, mostly during the spring influx coming up from the south, but also sometimes after the summer monsoons. I don't get them in any kind of numbers here in town, and some years none at all are seen. But I've had influx P. sennae and philea, A. clorinde and resident E. nicippe use my senna at times. I've seen A. maerula here a couple of times too, but have not seen them lay on my senna. I no longer rear leps, gave all my cages/sleevs, etc away. So I have not reared these species for many years, and when I did it was from livestock I collected in SE AZ for several years.

Very nice ab of P. philea.

A pair that I reared years ago...

I like butterflies as well, however, I only collect North American Lepidoptera and with less than a thousand species, you eventually gravitate to moths. I am currently rearing Charidryas gorgone from females I collected in Harrison County, IN.

I have a trip to Colorado and Wyoming for Schinia moths then end of August. I also will keep an eye open for butterflies. Its just an addiction.

I will visit Kill Pecker Dunes, Sweetwater County, WY to look for Schinia avemensis. It is a Dune species and Kill Pecker Dunes is the right habitat. Its just an addiction.