Rearing notes for cynthia silkmoth (Samia cynthia advena) second instar larvae. Stock originated as pupae from Pennsylvania. ​

Rearing notes 7/22/17-7/25/17​: 

Rearing notes for cynthia silkmoth (Samia cynthia advena) first instar larvae. Stock originated as pupae from Pennsylvania. 

Rearing notes 7/17/17-7/21/17:

Our cynthia silkmoth (Samia cynthia advena) eggs have started to hatch. Stock originated as pupae from Pennsylvania, November 2016. 

After about ten days, the cynthia silkmoth (Samia cynthia advena) eggs have started to hatch. About 40 so far. 

The newborn larvae look similar to the ricini (Samia ricini), obviously, but they aren't exactly the same. The cynthia look to have bigger black markings and their hair is white, not black. The cynthia are shown on the top row; the ricini are on the bottom.

Like the ricini, they group together immediately as they hatch, regrouping quite quickly when broken apart. We put the larvae all on sweetgum (Liquidambar). The only other option was Prunus, namely plum, which we don't have a whole lot of good quality leaves of. The sweetgum should work for these, as it did with the ricini, but in our experience these larvae are so polyphagous that they will pretty much eat anything initially. You can't tell for sure if a host is suitable until the fourth or fifth instar. . . So far there have been a few nibbles. 

We have collected some eggs laid by our first female cynthia silkmoth (Samia cynthia advena).​

The first of our two female cynthia silkmoths (Samia cynthia advena) that paired twice (leaving the other female without a mate. . .) a few days ago managed to squeeze out a few eggs. She laid quite a few on the first two nights, but after that seemed to completely loose interest. We have always had troubled with getting these saturniids to lay eggs, especially the Atticini. In total we only managed to get 62 out of her before she died, still with a rock hard abdomen probably containing some 200 eggs. 

We have put these 62 into the incubator since its getting quite late considering we only have about five weeks before we leave for New York. We're not sure what host plant we will use for these once they hatch. Obviously, tree of heaven (Ailanthus altissima) would probably be preferred, but we don't have that anywhere here. The top two alternative that we are considering are sweetgum (Liquidambar), which our second instar Samia ricini seem to be doing exceptionally well on, or plum (Prunus) which was the best host for our previous Samia ricini rearing.

Rearing notes for our cynthia silkmoths (Samia cynthia advena). Stock originated as overwintering cocoons from Pennsylvania, 2016. 

Rearing notes 7/1/17-7/7/17:

​Authors
Brian Liang

Today we had two more cynthia silkmoths (Samia cynthia advena) eclose, one of which (thankfully) is a female. We are still somewhat in disbelief that these cynthia silkmoths emerged so close to each other and at about the right time that they would in the wild while exposed to the most unnatural conditions. We still don't know when exactly they decided to break diapause and why. 

The female is not much larger than the males in terms of wing area, but of course it is much fatter. This particular female has slightly wrinkled wings, but that is probably a result of us disturbing it just slightly while it was expanding. It looks much darker in color than any of the males, a bit closer to the chocolate brown of Samia ricini. 

We are going to put all of the moths into a tub and try to let them pair by themselves. This shouldn't be a problem, based on what we have seen with ricini. However, these are distinctly wild and are extremely active. If it doesn't work, we can place them in an actual flight cage, but it's doubtful it will come down to that.  

Our cynthia silkmoths (Samia cynthia advena) have begun to eclose. Stock originated as cocoons from Pennsylvania. 

After a long, ambiguous wait, one of our cynthia silkmoths (Samia cynthia advena) has finally eclosed. We originally put these in the fridge in January after confirming that they were in diapause and then took them out again right at the start of May and put them in the incubator at 80 °F. When they didn't eclose by mid-June, we knew something was obviously up. Just like the imperials (Eacles imperialis) that don't normally eclose until late summer, they must take some pretty specific cues or simply have some kind of internal timer to make sure that they come out the second the weather warms up. So, putting them in the incubator probably wasn't enough.

At that point, we fished out five cocoons (we started with six) from piles of other cocoons and pupae, including Samia ricini, from the incubator and turned it off to help with the utility bill. After weighing, we confirmed that one was dead and tossed it. The remaining four were left in a cardboard box. 

Even though we knew we had missed one of the cocoons, it still was still surprising when we found this incredibly colored and crisp male in the incubator today. It was unmistakable as cynthia and not the, what now seems quite hideous, ricini. This true cynthia, perhaps also somewhat inbred at this point, is still a very robust and wild-like moth. The thing's perfectly clean and well shapen wings are a beacon in the legion of crippled and deformed ricini's that also recently eclosed. Not to mention, they are a lot bigger and much more functional. 

The coloration of this male cynthia is also completely different than the drab ricini. The dark, chocolate brown of the latter is replaced by a fine goldenish tan. The vertical stripes are also lined in the most glorious pink that provide a much needed contrast. In general, the patterns on the wings and the body are also just so much more defined. Those ricini's are truly some sad creatures. . .

As our six cynthia cocoons (Samia cynthia advena) are at least six weeks old, we assume they are all diapausing and thus placed them in the refrigerator at 40 F° (4-5 C°) for overwintering until March or April. 

- Alan

Today we had six cynthia and four Jacobs' silkmoth cocoons arrive. They are freshly spun but we do not know if they are diapausing, though we will know in the next few weeks based on if they eclose or not. Regardless of when they do, we plan to obtain pairings and eggs from them.

Above are the cocoons of the cynthia silkmoth (Samia cynthia advena). The Samia genus is taxonimically ambiguous, but these should be the subspecies advena, which refers to the population in eastern North America that was introduced from China in the late 1800s in attempt to start a silk industry. They are very closely related to the eri silkmoth (Samia ricini) that we have and are currently rearing which is also a species used in the silk industry.

The cocoons are somewhat irregularly shaped, being generally narrow and tapered at both ends, though more so at the top. Three are still wrapped in the leaf of some plant. They are slightly narrower and more compact than our old eri Silkmoth cocoons as seen in the comparison in the bottom two photos. As for color, the cynthia cocoons are a light tan while the eri's are almost white. In grams, they weigh 1.5, 1.7, 1.8, 1.9, 2.7, and 2.8 respectively, which averages to 2.07 each. However, the masses are clearly bimodal, with heavier suggesting female and lighter suggesting male, meaning we likely have two females and four males. 

The general life history of the S. c. adevena is probably extremely similar to that of S. ricini, and will therefore also be extremely easy to rear. The caterpillars utilize ailanthus (Ailanthus altissima) in the wild but will take a variety of alternatives in captivity such as Prunus and Ligustrum which we will use if the moths eclose next spring. However, if they are not diapausing and we must rear the caterpillars this winter, we might have to experiment with citrus (Citrus) which we are currently feeding our ricinis. We look forward to seeing the differences between each life stage of S. c. advena and S. ricini. 

And here (above) are the Jacobs' silkmoth (Rothschildia jacobaeae) cocoons. This species is endemic to Argentina and is part of the very diverse Latin American genus Rothschildia (Rothchild's silkmoths). The genus is said to be the New World relative of the Asiatic genus Attacus based on adult morphology (they look quite similar, being primarily brown with large transparent portions on each wing), though this could be symplesiomorphic so their taxonomic relationship is still debated.

The cocoons are shaped somewhat like those of Hyalophora cecropia but are much smoother and less tapered at the top. They are a light brown and quite thin, caving in easily when pressed. It does not look like there were ever leaves attached to them due to the very perfectly smooth surface, though there are indentations on the ventral sides where the twigs were removed. In grams, they weigh 2.5, 2.8, 3.6, and 3.8 respectively which averages to 3.18 each. However, just like the cynthia cocoons, the masses are bimodal, with heavier suggesting female and lighter suggesting male, meaning we likely have two females and two males. 

​We have not yet raised a Rothschildia species yet (though we have unsuccessfully attempted to rear the allied Eupackardia calleta once), so we really don't know much about them let alone any specific characteristics of this particular species. For example, we aren't even sure what hosts plants R. jacobaeae utilizes in captivity. Though fortunately, the caterpillars (like most Attacini silkmoth larvae) should be able to use various plants in the Oleeae tribe (family: Oleaceae) such as ashes (Fraxinus sp.), privets (Ligustrum sp.),  common lilac (Syringus vulgare), and possibly others. If any of these fail, we can try other typical Rothschildia or Attacini hosts if they are available, such as Prunus and possibly Citrus. In the case that these cocoons are not diapausing and we have to rear them this winter, then we plan to use glossy privet (Ligustrum lucidum), the only local species of privet we have, or citrus. Until then, we have both these and the cynthia cocoons placed in a plastic box lined with paper towels and lightly misted. 

- Alan