Paradirphia fumosa, or the Smoky Emperor Moth, is a very rarely studied species of Saturiidae, that is endemic to Mexico – where they are reportedly found in the provinces of Sinaloa and Durango. Only a handful of people in the world have ever photographed or reared them. Here, the insect is found on a higher altitude in mountainous environments; the parental generation of the insects pictures on this page was reportedly found on an altitude of 2000 metres. 

Most unique is the habitat; reportedly, it is frequently shrouded by a thick mist in the early morning, which creates an atmosphere of extremely high humidity – only for it to evaporate when when the sun rises and warms the environment up, causing a natural cycle of  humid cold nights and mornings into naturally hot and dry daylight hours. Thus, one can imagine that in captivity, the insects appreciate being very well-ventilated and dry most of the time, but also with frequent cold mistings of water.

The host plant of these Saturniidae in the wild, is to my knowledge, yet unknown to science. In captivity however they accept various types of Salix and legumes such as Robinia, Gleditisia and more. 

• Difficulty rating: Moderate (Not hard  to breed but  you need some experience)
• Rearing difficulty: 6/10 (From egg to pupa)
• Pairing difficulty: 7/10 (Archieving copulations)
• Host plants: In captivity, they readily accept Robinia, Salix,  Gleditisia and more. The wild host plant is unknown to me.
• Natural range:  Mexican (endemic) Sinaloa and Durango
• Polyphagous: yes; prefers Fabaceae and Salicaceae in captivity
• Generations: Univoltine; obligate pupal diapause
• Family: Saturniidae (silkmoths)
• Pupation: Cocoon (silk encasing)
• Prefered climate:  Cool and humid nights and mornings, but  try and ventilated daytime
• Special notes: Very rarely reared in captivity!
• Estimated wingspan: 45mm-65mm (medium sized)
• Binomial name: Paradirphia fumosa (R. Felder & Rogenhofer, 1874)

There is no doubt that Paradirphia fumosa is one of  the rarest species I have raised in my lifetime. Below I will share some pictures and observations.

The eggs of Paradirphia fumosa are bright yellow when freshly laid.  On room temperature, it  takes over a month for the caterpillars to hatch; which is not uncommon for the Hemileucinae subfamily.   The eggs are easily incubated on a temperature of 18-21C and develop in 4-5 weeks time.

A couple of days before they hatch however, the eggs will turn grey. Unlike other Hemileucinae, I failed to observe the “black dot” of fertility in the micropyle (the micropyle is hardly visible). I did moisturise the eggs once a week by misting them with water.

Then, after about a month, tiny caterpillars will appear. Their head capsule is black and their bodies are brown-yellow. Once born, they do not have an appetite yet – they will patiently wait for their brothers and sisters to hatch, before gathering in a group.

In captivity, rearing experiments have succeeded on various plants such as Robinia, Gleditsia and Salix. The question is: do they accept more host plants than these? The answer is: we don’t know. Since only a handful of people have ever raised this insect, there is only a limited amount of host plants that have been found for them yet. It’s clear that they are very fond of various legumes (Fabaceae) however. Experimentation with these types of plants could pay off.

This species did not seem difficult to rear for me, personally. I raised them in plastic boxes all their lives, from egg to pupae. However, since I read online that in the wild these animals have “humid, cold nights” but “hot and dry days”, I went as far as to open the lid of their container during the day so it could completely dry out, before spraying them at night and putting the lid back on. This strategy seemed to work well.

The second instar looks like the first instar, except that their colour becomes darker. They have something between a brown and wine-red shade with black head capsules.

In the third instar, the spikes become more pronounced. The larvae develop dark (almost black) bodies with bright dark red head capsules. The third instar is still social.

The first three instars can be raised in tiny airtight boxes. The firth and fourth instar, I usually move to very large (50L-100L) rearing containers. Many larvae can be raised in the same boxes; this social species does not mind company if they are kept clean.

In the fourth instar, the larvae develop pronounced reddish spines and bright red head capsules. In this instar, when touched, the spines will have an urticating effect (venom). From my observations in captivity, the urticating effect of this species seemed weak; although these insects were raised in captivity and thus we cannot extrapolate it to their venom composition in the wild, which may or may not be different. Despite that, the urticating effect seemed rather weak compared to some members of the genus Automeris or Dirphia, sometimes hardly noticable. That being said, humans are not their typical predators and it may still be effective enough against much smaller vertebrates that prey on them.

Interesting to know is that Paradirphia fumosa never becomes solitary. The larvae can be seen feeding in groups, even in the final instar. Although they do tend to form smaller groups with less individuals, because it’s difficult for many large larvae to compete over a few leaves. Sometimes they would randomly scatter, almost as if they are solitary, but then manage to find eachother again and feed in smaller groups that had 2 to 10 individuals. They will eat a lot, both during day and night, although in the darkness the larvae do wander more.

L4 and L5 look similar; but the final instar (L5) they can be distinguished by their typical pink head capsule, whereas in the fourth instar (L4) the head capsule is rather red than pink. The prolegs are also pink, and the spines on their backs are rusty-red.

The first instars were raised in completely airtight plastic boxes with no ventilation (L1, L2, L3) with little losses. Although I did “air” out their container by removing the lid for about one hour per day, to give them a daytime that was more dry than their nightttime. At night, I misted them with cold tap water. I fed them Salix capraea exclusively with little losses.

The final instars (L4, L5) were raised in a very large plastic rearing container; 100 Liter capacity “Dragonbox” (59 x 46 x 50 cm ) with a thick layer of paper tissue towels on the bottom. On top of that, small empty wine bottles containing tap water and citting of Salix capraea would be replaced every 2-4 days with fresh cuttings.

The container had an in-built lid that can open from two sides and lock. During the day, I would open it completely, exposing the larvae to fresh dry air. They had no interest in climbing out as long as food plant was provided; but it’s also hard for them to scale the slippery plastic walls.

Paradirphia fumosa, like all other Paradirphia I have raised, do not spin cocoons but prefer to pupate underground. In captivity, prepupae can be contained in airtight plastic containers with no ventilation, and a substrate of moist paper tissue. Here, they will pupate seemingly without problems.

I was able to raise 69 pupae out of (estimation) about 100 eggs. A decent survival rate. I actually had almost zero losses in the first few instars. But in L4 and L5, a small amount died for unknown reasons. In L5, I also lost a few individuals who failed to pupate and died as prepupae.

To me, rearing them seemed rather easy. Which is suprising, because other breeders who have bred this rare species, often consider them to be difficult. I guess that I accidently managed to find the right conditions for this species. You see, breeding species which are poorly documented to science, is always a bit of a gamble. Sometimes you just don’t know what they like; and you make an educated guess.

Credit where credit is due – it is the advice of my good friend “Bernard” who, with respect for his privacy, I will only mention by his forename; but is one of the most talented and knowledgable people I’ve ever met, especially when it comes to Central American Saturniid species, that helped me succesfully breed this species, by providing me accurate information and descriptions of their habitat. I simply just tried to recreate the conditions which he described in his personal communication with me, and I guess I hit the jackpot.

This species seems to be univoltine. I’ve only been able to produce one generation a year. The pupae must overwinter. I overwinter them at moderate temperatures between 10C and 16C in basement. Every year, the moths consistently appear around July (in captivity). I am not sure if this is their flight time in the wild aswell, but surely they are strongly synchronised. Males and females never hatch far apart for me; within 2 weeks time the majority of the brood usually appears from the pupae.

This species is slow growing; most caterpillars in the rearing depicted on their page hatched from their eggs (L1) by September 1, 2020. However, only half of them started showing interest in pupating by November 13, 2020 – a total rearing time of 2.5 month (73 days) around room temperature (18C-21C).

Paradirphia fumosa is a wonderful species to see. The wings are black, fading to grey below the submarginal area. They have a beautiful golden frill on their hindwing costa, as if they have been subtly coated with leaf gold. The forewings of both males and females have two rows of creamy yellow spots that are connected by a subtle, fading line of yellow scales. The thorax is very hairy in both males and females; they have two large brushes of hair covering their wing muscles. The fact they are so dark coloured and hairy perhaps indicates that the appearance of this species is optimised for heat retention (black surfaces absorb more warmth from sunlight) which helps facilitate their diurnal activities.

The abdomen and legs of Paradirphia fumosa are bright red. If touched, the moths will fold their wings behind their back, and curl up their abdomens; a threat pose that is commonly seem in many members of the Hemileucinae subfamilies (Dirphia, Periphoba, et cetera). The red abdomen has black stripes aswell; and in females, the threat pose also exposes the naked yellow cuticle between their abdominal segments.

Interestingly, it’s quite hard to get the males to do a threat pose, and if they do, it’s very brief. Females will curl up and remain in the threat position for several minutes however.

The species is diurnal and males strongly respond to sunlight.

Pairing Paradirphia fumosa is the trickiest part of their life cycle. When I first obtained eggs of this species, I did not believe my friend who told me males and females can only pair if they hatched on the same day from their pupae. But it seemed to be mostly true. The only pairings I was ever able to obtain, were of fresh males and females less than 12 hours old.

It just seems this species has a short lifespan. In 24 hours, most specimens are exhausted. Especially the hyperactive males who frantically bash themselves against the cage walls in captivity; tearing their legs, wings, antennae and passing out from exhaustion.

This begs the question; is the situation the same in the wild? Well, that is difficult to say. I don’t like to extrapolate observations in captivity to what happens in the wild. In the wild, the animals are not contained in small pop-up cages, and probably recieve less damage since they’re not constantly making friction with the cage walls they keep flying into. But it does seem they have a rather short lifespan. Most of them pass away in 3 to 7 days (females live longer as usual). Males in particular are hyperactive and if they fail to find a partner, flap themselves into exhaustion.

This species is diurnal (day-active). My method to pair them is as follows: the males and females tend to hatch at night from their pupae. I take the fresh males and females, and I place them in the fridge around 7C. These conditions resemble the cooler nights in their habitat.

Then, I wait until the sun comes up. The moths tend to hatch around July in captivity; one of the hottest months of summer. I wait until 14:00 to 15:00, before I take them out of the fridge, and place them in a small pop-up cage in my garden, in full sunlight.

The sudden transition from the “cold and dark” fridge to being blasted with full sunlight outdoors (25C+) immediately activates the males and females; which start calling (female) or frantically flying around (male). Within 5 to 10 minutes, most couples paired up. If they fail to pair, I put them back in the fridge and try again next day.

Is it difficult?

I think they are somewhat easy to breed. But that’s because I have figured out what they need in captivity. Even easy to breed species can be difficult when we have no clue what they like! That’s the downside of breeding species, of which very little information and pictures exist; there are no caresheets and not much people who can give you tips. But once you figure them out, and write everything down and repeat the method, it becomes easier. Now everyone can do it! Including you. That is; if you ever manage to obtain eggs of this species. Which is unlikely; it’s still a bit of rarity. But if you do then congratulations; I hope this caresheet helps you!

Thank you for reading my article. This is the end of this page. Below you will find some useful links to help you navigate my website better or help you find more information that you need about moths and butterflies. 

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Citations: Coppens, B. (2020); Written by Bart Coppens; based on a real life breeding experience [for citations in literature and publications] 

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