Category: Samia_ricini

Samia ricini L4 Rearing Notes (7/20/17-7/??/17)

7/25/2017

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

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

7/25:

Well, there we have - 1.3 g larva and not even in apolysis yet; at least one other was also 1.3 and many others were 1.0-1.2 g; it will be interesting to see how big they can get next instar on Liquidambar

7/24:

The larvae quite large now, with the largest at 1.1 g and many others 1.0 or .9 g; in previous rearings, larvae never exceeded 1.2 g, so these are either full grown or very close to; possibly, they may even exceed 1.2 g as Liquidamber has seemed to be quite a good host based on their extraordinary growth rate (last rearing, we had them in the incubator at constant 80 °F and they spent five days this instar; this time they are at room temperature (highest day temps only mid 70s) and it's only been four days so far)

7/23:

The larvae continue to grow very quickly, stripping large branches of leaves now; based on head to body ratio, probably near full grown now

7/22:

The larvae are much larger now and feed much more; their growth rate seems to be increasing significantly each instar, as the early instars took the longest, perhaps because, as a very polyphagous species, they had not become accustomed to the host yet and were digesting it poorly

7/21:

The larvae have grown rapidly, becoming plump and white

7/20:

Several of the larvae molted to fourth instar after having spent seven days in third instar
The fourth instars are still slightly gregarious and acknowledge each other presence, though tight aggregations are not crucial; their head capsule have become yellow and tubercles enlarged

Authors
Alan Liang

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Samia ricini L3 Rearing Notes (7/13/17-7/19/17)

7/19/2017

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

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

7/19:

Several larvae entered apolysis and are about 20 mm in length, consistent with measurements from previous rearings, so Liquidambar has proven to be a good host so far

7/18:

The larvae are beginning to become more scattered across the cutting rather than in tight aggregations
The larger larvae are becoming yellowish ventrally

7/17:

Larvae have grown very quickly and some are near full grown

7/16:

The larvae are much larger and white than before and are feeding surprisingly large amounts of sweet gum for their size and numbers
Though we don't know if it is possible due to having been domesticated, but we put the larvae in an opaque tub to control and limit the amount of daily light they receive in attempt to induce diapause when they pupate

7/15:

White powder is beginning to accumulate dorsally on the larvae

7/14:

Several more molted into third instar; they are beginning to aggregate again and have grown quickly

7/13:

The first few larvae molted into third instar after spending six days in second instar
These third instars look more or less the same as ones we have always seen in previous broods, though perhaps yellower than when reared on Prunus

Authors
Alan Liang

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Samia ricini L2 Rearing Notes (7/7/17-7/12/17)

7/12/2017

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

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

7/12:

Many larvae entered apolysis and became yellow and are 10 mm in length

7/11:

The larvae have become plump and with taut cuticles, probably near the end of this instar

7/10:

The larvae are much larger again but are slightly diverging in size, though still remaining highly gregarious

7/9:

The larvae are growing much quicker than in the previous instar and seem to be doing especially well due to feeding them the soft new growth of sweet gum

7/8:

All the larvae have molted to second instar now and the older ones have already fed and become greenish

7/7:

Several of the larvae molted into second instar with others clearly close behind; they spent a rather long 10 days in first instar but look very healthy

Authors
Alan Liang

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Samia ricini L1 Rearing Notes (6/27/17-7/??/17)

7/5/2017

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

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

7/5:

A few larvae entered apolysis, measuring about 7 mm

7/4:

Larvae are very bright yellow and plump now and have become slightly stubbier and compact

7/3:

Larvae are becoming yellowish and plump, probably close to full grown now

7/2:

Larvae continue to grow much larger, and are now mostly aggregated into one large group in the center top of the leaf

7/1:

Now the larva on sweet gum look quite good, becoming much larger and greener, with tighter cuticles

6/30:

The larvae are slightly larger and greener but are still quite small

6/29:

The larvae on sweet gum have actually shown good improvement; all seem to have settled down and feed, aggregating into large groups

6/28:

Several hundreds, perhaps even a thousand, more have hatched; at a loss as what we were supposed to do with them, we decided to sleeve them all onto a group of plum (Prunus) saplings and apple (Malus) (not at all concerned about high mortality might be) and left them there until further notice. . .
The hatchlings from yesterday have initiated feeding on the sweetgum (Liquidambar) but don't look to be doing that great on it; some clearly did not feed so we are unsure whether the ones that did are simply eating it because they are more or less willing to eat any kind of leaf at birth (we have seen this in the past) but not actually able to survive well on it

6/27:

See Samia ricini Eggs Start Hatching

Authors
Brian Liang

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Samia ricini Eggs Start Hatching

6/27/2017

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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.

Authors
Brian Liang

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First Eri Moths Eclose

6/11/2017

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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.

Authors
Alan Liang

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Samia ricini Rearing Notes (5/16/17-5/28/17)

5/28/2017

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Rearing notes for our eri silkmoths (Samia ricini). Stock obtained as eggs, March 2017.

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

5/28:

All prepupae have finished spinning cocoons and most have already pupated; all eight naked pupae have pupated - UPDATE 5/31/17: placed all cocoons and pupae in the incubator at constant 75°F/24°C
Mass of all 33 cocoons and eight naked pupae were measured; disappointingly, the average is much lower than what we had expected based on last year's rearing (2.22 g, n=14), and the variation was quite high, though it would most likely be a lot lower had we been able to sex them
Cocoon mass (g) (n=33): 1.2, 1.3 (2), 1.4 (4), 1.5 (2), 1.6 (3), 1.7 (5), 1.8 (4), 1.9 (3), 2.0 (2), 2.1, 2.2, 2.3 (2), 2.4, 2.5
- Mean: 1.773
- SD: 0.337
- Med: 1.7
Naked pupa mass (g) (n=8): 1.2, 1.3 (3), 1.4, 1.5 (3)
- Mean: 1.375
- SD: 0.116
- Med: 1.35

5/27:

A few more naked prepupa pupated; the on from yesterday has already almost finished tanning
Based on sound and feel, many of the prepupae inside the cocoons have pupated already

5/26:

All larvae have finished spinning their cocoons except one, but it is already a prepupa
One of the naked prepupa pupated into a male pupa; it is yellow when teneral

5/21:

Collected the completed cocoons and naked prepupae, with amount to 2-3 dozen or so; there are still some that have yet to spin
So far the mass of the cocoons/prepupae are quite good assuming they don't drop too much upon pupation, as most naked prepupae are 2+ g and some large cocoons are 3+ g; it seems this lineage's larvae shrink much less prior to pupation compared to our former lineage, despite obtaining only modest sizes in the fifth instar

5/20:

Almost all larvae have spun cocoons, with the few remaining likely to follow very soon; due to disturbances, some of the prepupae abandoned or failed to spin cocoons and just pupate as naked prepupae

5/19:

Most larvae have spun cocoons now; some completed ones are actually decently large

5/18:

Many more larvae have spun or are in the process of spinning
The finished cocoons are very white and have a more cotton-like texture than the ones produced by our former lineage; they still weigh a surprisingly decent amount - a randomly selected completed cocoon was still 2.8 g, though it will likely shrink quite a bit by the time the larva inside actually pupates; perhaps this lineage's larvae obtain lower mature masses but shrink less upon pupation than our other lineage

5/17:

Several more larvae have become prepupae
The older prepupae have already started spinning or have already spun cocoons among the plum leaves; the cocoons are indeed slightly more rounded that the previous lineage we reared last year, though are much smaller than the cocoons of its own lineage from the previous generation

5/16:

Two larvae had runny frass and became prepupae, they have shrunk and become yellowish, weighing only around 3 g now

Authors
Alan Liang

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Samia ricini L5 Rearing Notes (5/1/17-5/15/17)

5/15/2017

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Rearing notes for our fifth instar eri (Samia ricini) larvae. This is our newer strain, obtained Spring 2017.

Rearing Notes 5/1/17-5/15/17:

5/15:

The largest larva is now at 5.7 g and many are in the 5 g range as well, which isn't so bad anymore; if they can all break 6 or 7 g that would be quite good

5/14:

The larvae's grip on the plant seems to have gotten much weaker as they have become larger due to their heavier weight and probably the wearing down of the crochet hairs
Quite surprised that none have become prepupae yet as these larvae have already been in fifth instar twice as long as the ones we reared last summer
The largest larva on the milk covered leaves is now 4.1 g

5/13:

Larvae have more or less stopped growing and are mostly in the 4-5 g range; rather unimpressive but hopefully there will be a little more growth before pupation

5/12:

The largest larva is at 5.5 g; the largest larva on milk coated leaves is 3.6 g
Many of the former larvae on privet died, having failed to switch onto the plum, but those that did look fine

5/11:

The largest larva is at 5.1 g now, so starting to slow down; was expecting much larger then this
The larvae on privet were doing extremely poorly, growing very slowly and undersized; we switched them onto plum and so far some have already started feeding on it

5/10:

The larva feed much more now, stripping large branches of plum; the largest larva is at 4.8 g
The larva on milk are younger than the ones on regular feed, but the largest is at 3.0 g

5/9:

The largest larva has reached 4.3 g which is still a ways behind the 7+ g larvae we reared last summer; now sure why these would be so much smaller when they were reared in similar ways

5/8:

The larvae fed a lot and seemed to have grown quite a bit since yesterday, but weighing them revealed disappointingly that the largest was only 3.8 g
The milk fed larvae were able to feed on the milk soaked leaves normally and digest the lactose, as none regurgitated/had diarrhea; don't know if it will really make a difference
The privet larvae have begun molting into fourth instar and are still small and growing very slowly; in fact, the fourth instars who high levels of melanization, retaining third instar-like traits such as an black and yellow head capsule rather than a completely bright yellow one; this means they are smaller than would be ideal for fourth instar

5/7:

The largest larva has grown to 3.5 g; many of the others are in the 3.0 g or high 2.0 g range
We took out most of the younger fifth instar larva and placed them on plum cuttings soaked in milk and stuck in a flask of water and plant fertilizer solution in order to fortify to leaves; the milk experiment has been done on Bombyx mori and has shown to increase larval size, so hopefully we can produce larger larvae this way; so far the larvae feed on the leaves normally

5/6:

Larva are beginning to pick up speed, looking much plumper with tighter cuticles and firmer bodies; the largest is at 3.1 g and many others are in the high 2 g range

5/5:

Larva are slightly larger now, the largest being 2.6 g
Unlike when freshly molted, the larva have mostly stopped regurgitating when disturbed; it seems this behavior is most common with freshly molted larva of most Lepidoptera species that do it

5/4:

Fifth instar larva are now much larger and firmer rather than soft and loose skinned; the surface of the cuticle has grey freckle like markings and the dorsal tubercles look slightly yellow
The largest larva is now 2.2 g
The third instar privet larvae are looking better now, becoming whiter and plumper and feeding a good amount

5/3:

Larvae frequently regurgitate reddish fluid when disturbed, making it difficult to change food; however, this behavior seems to be most common at the beginning of each instar

5/2:

Most all of the plum feeders molted into fifth instar and are very healthy and robust
We transferred all of them onto the plum cuttings and mixed in some hawthorn (Crataegus), another Rosaceae, to see if we could feed them on both; so far it doesn't look like they can tell the difference between the two hosts, feeding on them interchangeably

5/1:

Two of the larva molted into fifth instar after a relatively short six days in fourth instar
Fifth instars have lost their white powder as it was shed off with their former cuticle, but should accumulate quickly again; other than that, they look more or less the exact same as before except more developed tubercles and the absence of any black spot like markings on the body whatsoever
We transferred the plum feeders onto a cutting placed in a water vase as the container in the incubator was to small for them, especially going into fifth instar

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Samia ricini L4 Rearing Notes (4/25/17-4/30/17)

4/30/2017

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Rearing notes for our fourth instar eri (Samia ricini) larvae. This is our newer strain, obtained Spring 2017.

Rearing Notes 4/25/17-4/30/17:

4/30:

Several larvae entered apolysis and are very plump with tight cuticle; the largest ones are at 1.2 g, which is larger than any fourth instar from the previous broods; not sure if the larger size is due to the spring leaves being more nutritious, the incubation, or the fact that this is a new lineage in which case it would be a genetic reason
The third instars on privet are doing quite well now, feeding a good amount and becoming white and powdery

4/29:

The larvae couldn't tell the slightest difference between the two new Prunus species we offered them yesterday and the old variety, feeding voraciously as ever
The largest larvae are at 1.0 g which is quite good already; hopefully they can push a few more decigrams

4/28:

The fourth instars have grown slightly larger, at 0.8 g which is still considered small for this instar; perhaps the heat from the incubator is making them smaller, as Saturniids reared under hot temperatures tend to be smaller than when reared under cooler conditions
We offered the larvae some different plum species, Prunus domestica and Prunus salicina "Santa Rosa" because we didn't want to kill the Prunus cerasifera in our backyard (saving it for the cecropias)
The privet larvae are molting into third instar now

4/27:

Larvae are voraciously devouring plum leaves now and have grown to 0.7 g up from 0.4 g
The white powder voting is very thick and rubs off easily when touched

4/26:

Larvae on plum look significantly larger than yesterday and now weigh 0.4 g; the white powder coating has become thicker as well, making them look very white
Though difficult to tell due to the overcrowding, the larvae seem to be losing their gregariousness and don't mind feeding alone now
The larvae on privet are doing very well now except they are far behind those on plum, but otherwise look very plump and healthy

4/25:

The larvae on plum molted into fourth instar, spending a short four days in third instar; they are now 0.3 g and measure about 20 mm still
The fourth instar larvae look similar to the previous instar, except whiter with more developed scoli and a yellow head and legs
After putting the privet feeders in the incubator at 26°C with the plum feeders, they have made much faster progress but are still in second instar, though much healthier and stronger looking than before the incubation

Authors
Alan Liang

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Samia ricini L3 Rearing Notes (4/21/17-4/24/17)

4/24/2017

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Rearing notes for our third instar eri (Samia ricini) larvae. This is our newer strain, obtained Spring 2017.

Rearing Notes 4/21/17-4/24/17:

4/24:

Many of the larvae on plum have entered apolysis; they are somewhere between 0.2-0.3 g

4/23:

Larvae have all become large and white, feeding at more than twice the rate they were before; the branches were completely stripped clean by noon today after being changed the night before
The largest larvae weight 0.2 g and are 20 mm long; these were also the full grown measurements for the past two broods we have had, but it is likely that these larvae are not yet full grown yet and will surpass these numbers

4/22:

The larva on plum have become incredibly voracious and fast growing, stripping many branches of plum clean - its hard to believe its only been a day when looking at yesterday's photos;
The larva have grown to 18 mm and have acquired a thin film of white powder

4/21:

Many of the larvae on plum molted into third instar after spending just three days in second instar
The third instar larva have already fed and grown a bit, and are 12 mm in length; compared to last isntar, their scoli are much larger and their bodies are much whiter rather translucent green
The larva on privet are just beginning to molt into second instar

Authors
Alan Liang

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