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Cecropia larvae rearing

Cecropia rearing

Hello all! I am a relative newbie in raising giant silk moths. For the past 4 summers, I have (mostly) successfully raised multiple generations of Polyphemous and Luna moths. I am hoping you can give me advice on some issues I’ve been having with rearing cecropia larvae.

I obtained some Cecropia ova a few weeks ago, and they all hatched within a week. I put the larvae in 14 ounce plastic containers (5.5” in height, 4.25” in diameter). I put small pieces of leaves in the containers with no more than 4 larvae in each. I wasn’t certain about an ideal host plant, so I had a small willow leaf, a piece of what I believe to be cherry, and another that was maple. For the first couple of days, they seemed to be doing ok: they would climb up the sides of the containers, and then eventually back down, and I saw frass: evidence that they were eating. I opened the containers every day to check on them, but did not touch them. After a few days, they stopped eating and moving and I realized they were dying or dead.

I have read that cecropia are prone to disease and bacteria more than Luna larvae. Any ideas about what i could have done differently to increase the chances of their survival? The containers had plastic lids, so no airflow, except when I opened them. Should they have mesh lids instead? Or a small amount of moisture inside the container?

Thanks in advance!

Welcome To BugGuide
First observation - really interesting artwork. Second observation would be that when they start wandering around like you describe they are either looking for a place to hide during the day, a place to molt, a place to pupate, a place to die as they have been parasitized, or something to eat. Clearly the last option in this case.

So either the leaves were not from a plant they prefer or the presentation was off. It can occasionally be difficult to find a good match for species that are generalist feeders as there is the concept of local preference. As such it is a good idea to ask the person you obtain the eggs from what they feed theirs. Once that is accomplished provide them leaves still on a bit of twig as that offers them better opportunity to express their innate behavior. Feeding as a group or solitary, eating from the leaf tip back or petiole up, skeletonizing (a subject for an artist to explore), chewing random holes, and so on. The twig also provides a place to hide if they are a species that has that in their repertoire. Leaves as in more than one as some species prefer to retreat to a nearby leaf away from their feeding damage when resting.

With to respect to containing all this any will do. I use four sizes ranging from a small plastic container that came with sliced lunch meat to two gallon containers that I ordered from a supply company. The bottom of the container gets a moist paper towel, then I usually add a bare stick preferably from the same host plant. This spans the container from top to bottom. On this stick rests the host plant twig arranged so that the leaves are mostly elevated off of the bottom. Then a bit of mist to the side of the container to keep the humidity up. This is to keep the leaves from wilting which allows me to use the same twig for up to a week. The top is either that which came with the container or plastic wrap held in place with a rubber band. No holes for circulation are needed.

Daily I open up the container for observation, photos, fresh air, and removing frass accumulated on the paper towel. I used to change out the paper towel every three days but then a global pandemic struck and paper towels became a prized commodity. Now they are reused until they fall apart or just before I think the larva is about to pupate. When that time comes I throw in a fresh paper towel and some leaf litter (once frozen to kill off any deditrus feeders). If they use either of those - great. If not then one more thing to figure out.

Thank you, George: for the co
Thank you, George: for the complement, as well as the abundant information! I will be better prepared at the next opportunity. Have a great day.

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