This is an ongoing documentation of my experience rearing a group of 37*Parnassius clodius. They were obtained as F2 stock originating from a cross between 2 clodius originating seperately from Mt. Eddy, CA and Alta, CA.

OCTOBER 21, 2021: I've kept the group of about 40 eggs at 37*F since late August under complete darkness. I plan to remove them from the refrigerator around December when their Dicentra formosa hostplants are sufficiently grown.

January 11, 2021: I don't have a very large Dicentra plant right now, so I'm going test if clodius will accept a related plant: Fumaria capreolata. A two eggs were removed from the diapause chamber and placed in an open glass container 6 inches under a desk light and a heat lamp. They were lightly sprayed with water each morning but did not emerge as early as expected, so the heat lamp was removed on January 13.

January 13, 2021: Both larvae had emerged by the evening and were supplied a small leaf of capreolata, upon which they immediately began feeding. Each measured less than a millimeter in length.

January 14, 2021: The larvae are being exposed to 12-hour photoperiods to simulate a summer light cycle and are misted every morning. Two hydrated capreolata leaves are added daily but the larvae are so small that they consume only about 10 percent of each leaf. Each larva measures around a millimeter in length.
They are very poor climbers but move very energetically; almost twice as fast as other caterpillars of their size. When disturbed, they drop from their resting positions and curl up in a defensive position. They are highly reactive to changes in lighting and temperature; becoming lethargic when heat/light are absent at night and instantly starting to move when the light switches on.

January 15, 2021: The heat lamp was accidentally unplugged this morning and there were no signs of consumption on the leaves by evening. When the heat was reintroduced the larvae immediately "turned on" and began eating again.

January 16, 2021: The larvae grew more noticeably today; each is now over 3mm in length and slightly plumper. Their head capsules are looking disproportionately small against their bodies, so I predict that they will enter apolysis for the second instar within a few days.

January 17, 2021: The larvae ate a large amount during the night; one has entered apolysis for the second instar. Both larvae measure over 4 mm.

Major update: January 19, 2022: Both larvae managed to escape their small enclosure through a hole in the netting; both proceeded to walk directly on exposed duct tape, trapping themselves. Both larvae were dead. I immediately repaired my error and have started a second batch of 2 eggs. Hopefully, I'll be able to avoid making any more ridiculous mistakes.

January 27, 2022: I'm restarting my notes on a secondary larva hatched on 1/20/22. It was allowed one week of development under the same conditions/hostplant as the previous larvae and is thus around the same developmental stage. The larva underwent ecdysis to the second instar on 1/25/22 and currently measures 8 mm. At this stage, two bilateral dorsal rows of yellow spots are becoming visible.

Update: The larva developed to the fourth instar but measured only a centimeter in length. Upon such time it entered apolysis, failed ecdysis, and died. I would not recommend attempting to rear this species on fumaria unless you desire highly stunted larvae.

A summary of my ongoing experiences while rearing Attacus atlas. They are being reared indoors on Ligustrum lucidum (tree privet) that is replenished daily and treated with a hydrogen peroxide rinse to reduce chances of infection. Since emergence, the larvae have been exposed to 9 hour photoperiods under 2 45W incandescent lamps.

OCTOBER 1, 2021: A cohort of 57 Attacus atlas eggs of undisclosed origin arrived. They were placed in a dry, airtight plastic container with a paper towel at the bottom. (The temperature ranged from 68-72*F. Humidity was near zero.)

October 7, 2021: The first group of larvae emerged in the evening. They were provided with a sprig of Ligustrum lucidum but did not begin eating immediately, as is typical with many Saturniidae larvae. Their enclosure remained airtight to maintain humidity. (Temperature: 68-72*F, humidity: 90%+.)

OCTOBER 8, 2021: The rest of the larvae had emerged by morning and had begun eating the privet. 2 additional sprigs were cleaned and added into the enclosure. Each sprigs' end was wrapped in a small, moist piece of paper towel and tin foil for hydration. (Temperature: 66-72*F, humidity: 90%+.)

L1 larvae

OCTOBER 8-13, 2021: There were no deaths during this period. I changed their food every 24 hours and replaced their paper towel and cleaned their enclosure with a rinse of H2O2 every 12 hours. Humidity was kept at 90%+ to prevent desiccation, so I was being obsessively sanitary, hence the hydrogen peroxide. (Temperature: 66-72*F.)

October 14, 2021: Several (13) L1 larvae entered apolysis. Everything else proceeded as usual. (Temperature: 66-71*F, humidity: 90%, mortality: 0.)

October 15, 2021: Most (53) of the larvae had entered apolysis and the first 2 successfully ecdysed into the second instar. Everything else continued as usual. (Temperature: 67-72*F, humidity: 90%+, mortality: 2)

L2 larvae

October 16, 2021: Only 4 additional larvae ecdysed into the second instar, the rest remained in apolysis. There was very little eating that day. (Temperature: 67-72*F, humidity: 90%+, mortality: 1)

OCTOBER 17, 2021: 1 larva ecdysed into the second instar. Seven larvae underwent a failed ecdysis. Their head capsules popped off but they were seemingly unable to slough off their skins. In some cases, the fresh prolegs of the new instar could be seen protruding from the dried skin. The larvae that failed ecdysis were dispatched, as they were completely incapacitated by their old skins. (Temperature: 68-73*F, humidity: 90%+, mortality: 7, remaining larvae: 47.)

OCTOBER 18, 2021: 5 larvae ecdysed into the second instar. 11 underwent failed ecdysis and died. The second instar larvae displayed no signs of infection and continued to behave normally. (Temperature: 66-72*F, humidity: 90+%, mortality: 10, remaining larvae: 36.)

Sorry for the huge delay with updates, I've been a bit busy lately. I'll finish this post off with a more condensed recollection and analysis.

Around October 20th I had 16 larvae left because the rest had failed ecdysis, most likely due to the cold. A few (7) molted into L3.

young L3 larva

One larva became infected and I moved the rest to a net enclosure to give them some space, but more started becoming diseased so I resigned myself to raiding target for some small 6x3x3 tupperwares. At this point there were 8 remaining larvae that I separated into individual containers, cleaning each meticulously. The larvae were all now L3.

developed L3 larva

Disease took 5 more larvae by the end of October but the quarantine had managed to mitigate the spread, so I was left with 3 healthy late L3 larvae. I changed their food ant towels daily, rinsing their containers with a diluted H202 solution.

On November 1st the first larva molted successfully into the fourth instar but it was surprisingly small; barely 1.5 inches in length. It was at this point that the larva developed the signature turquoise hue of the atlas larva, as well as extended scoli. The orange abdominal patches were no longer present.

young L4 larva

On November 2, the first L4 larva got sick and died. The two remaining larvae shed into L4 in the following days. Those two made it to pupation.

From November 9th onward, the last 2 larvae ate constantly and developed well, reaching a large size of 5 inches in length at L6. I kept a heat lamp over their enclosures in addition to the light to encourage faster development. The plastic lids had only a few air-holes so humidity was at 99% percent most of the time, though that was of little concern to me because these larvae were living in completely isolated, obsessively maintenanced habitats. The smaller larva did experience a failed ecdysis but I managed to pull the skin off before it was too late. They ate about a dozen leaves a day.

left: young L5 larva, right: developed L5 larva with prominent scoli

They developed a thin powdery wax substance on their skin common on many attacini larvae and were very strong when gripping to my hand. Their coloration developed into a softer greenish-blue and they developed small light spotting patterns. The waxy substance seemed more concentrated on the dorsal scoli of the larva rather than the skin.

L6 larvae

By December 1 both larvae entered apolysis for the final time and were placed in pupation chambers. By the 4th, they had pupated and were kept under the heat lamp.

Pupa

One pupa collapsed into itself the day after it pupated and died, so I was left with only one.

I foolishly took it out of the container and placed it in a heated net-enclosure in a room with a humidifier, thinking these devices would create a sufficiently hot/humid environment until it emerged. The pupa eventually desiccated and died despite this.

Regardless of wether or not I got to witness a live adult, I did experience (amongst multiple individuals), the majority of the life cycle of this remarkable creature and am happy for having done so.

If I were to give it another attempt, I would rear them in the summer where the temperature isn't such an important variable to constant have to manage, as I believe low temperature may have been the underlying cause of many issues related to failed ecdysis (poor liquid diffusion) and stress (lowered rate of consumption), the latter leading to increased risk for disease. I would also separate them into many cohorts as soon as they hatched to mitigate infection. It would be a lot of work, but with a species as unpredictable as this I wouldn't leave anything up to chance. Hopefully this journal post helps to impart some useful and saving knowledge to anyone wishing to rear this awesome species.

Cheers!