Rearing Notes 8/6/17-8/14/17:

​Authors
Alan Liang

And another brood finished. The last of the larvae finished spinning, so like always, we collected all of them in a tub and weighed them. There are 20 in total, and this time they are quite large compared to previous rearings. This is our fourth rearing of Samia ricini; summary stats are listed below for this brood, as well as two previous broods (the third brood of winter 2016 was never recorded, but was very small). Note that this brood was reared on Liquidambar while the other two were on Prunus, and the fall 2016 brood was of a different lineage.

Summary Statistics for Samia ricini Cocoon Mass:
                                  Mean     Std Dev     Median     Min     Max     N 
Fall 2016                 2.221       0.356          2.1               1.6         2.8        14
Spring 2017            1.773       0.337           1.7               1.2         2.5       33
Summer 2017        2.218       0.294          2.19            1.78       2.86     20

The majority of cocoons this time were 2 g or larger which is quite good, and masses were less variable than in previous broods. Of the three broods, both the fall 2016 and summer 2017 broods were significantly larger in mean mass than the spring 2017 brood (p=0.0002 and p<0.0001, respectively), and between those two larger broods, there was no significant difference in mean mass. 

​Shown above are this brood's cocoons compared to the fall and spring cocoons. The spring are visibly much smaller, and the silk was thinner and and more papery, rather than thick and fluffy. The fall cocoons look about the same size visually as this time's cocoons, but as they were of a different lineage, the shape of the cocoons were flatter and less round.

Most likely the spring rearing produced small cocoons because of much more severe overcrowding in the final instar compared to in the other two and the food quality was not as good. Or, maybe it was the host plant species that made the difference, as this time we used Liquidambar for the first time rather than Prunus. Perhaps Liquidambar was a better host than Prunus, and the reason why the fall brood was on par with the summer brood because that lineage was larger or utilized Prunus more efficiently.

​Authors
Alan Liang

Rearing Notes 7/27/17-8/5/17:

Rearing notes for our eri silkmoth (Samia ricini) fourth instar larvae. Stock obtained as eggs, March 2017.

Rearing Notes 7/20/17-7/26/17:

Rearing Notes 7/13/17-7/19/17:

​Authors
Alan Liang

Rearing Notes 7/7/17-7/12/17:

Rearing Notes 6/27/17-7/??/17:

See ​Samia ricini Eggs Start Hatching

Our eri silkmoth (Samia ricini) eggs have begun to hatch in huge numbers. Stock obtained as eggs, March 2017.

A little over two weeks since the first eggs were laid, our eri silkmoth (Samia ricini) eggs have begun to hatch. Actually, they begun hatching yesterday, but only two of them did. Today, we found swarms of them. 

This is a bit strange since we know for a fact that, back those two weeks ago, more than two eggs were laid together on the first day of laying and not nearly as many eggs were laid on the second day. In past rearing, we have also noted that at Samia ricni have a strong tendency to hatch together from eggs that were laid a day or two apart. Most often, eggs that that supposedly should have hatched in consistent amounts over a week or more time would most all just hatch in one or two enormous bouts, later than when we would expect the first few to start hatching. This leads us to think that the earlier eggs are able to slightly delay their development so that they hatch together with their siblings in this highly gregarious species. Perhaps it is an absurd theory, but the fact still stands that eggs are very sensitive, living organisms that probably have many interesting properties that we may often overlook. 

Anyway, with our masses of newborn larvae, we were sort of at a loss as what we should actually attempt to do. There is absolutely no way that we are going to try to rear all of the thousands that hatch. For now, we dumped the larvae into a small tub with sweetgum (Liquidambar), a host that we have never tried for Samia ricini but that we have a seemingly never-ending supply of where we live. We will have to find out an ethical way of disposing of the excess larvae that hatch in the coming days. 

Our eri moths (Samia ricini) are beginning to eclose. Stock obtained as eggs, March 2017

A little over three weeks since our first ricini span cocoons (5/18), the first two eclosed. One eclosed in the morning and the other in the evening; both are males. The left hind wing of the first one is slightly wrinkled, both other than that both are perfect unlike last year's lineage in which a least half were badly crippled (common problem from inbreeding ricini). 

The moths are quite small, probably about the same size as promethea. The wings are brownish grey with white patterns, yellow crescents in the center, and a black spot at the fore wing tips. The body is white, the antennae are yellow, and the thorax is grey. These males have pretty narrow and falcate fore wings that often drape over the hindwings when spread, though usually the moths like to close their wings at rest. A relatively drab and familiar sight compared to most of the other Attacini, which are typically bright and flashy in appearance. 

The dull coloration of ricini, though, probably makes it quite cryptic on grey and brown backgrounds such as the ground and tree trunks, as shown below. 

Rearing Notes 5/16/17-5/28/17:

​Authors
Alan Liang