Gonimbrasia tyrrhea — “ZigZag Emperor Moth”

Our world is filled with exquisite species of moths. Yet, despite all the freely available natural splendor around us, few people (sadly) stop to think about them. Certainly among the most elegant ones is the African Zigzag Emperor Moth (Gonimbrasia tyrrhea).

This species is found in Congo, DRCongo, Kenya, Namibia, South Africa, Tanzania, Zambia and Zimbabwe. The submarginal line has a zigzag-like pattern; giving them the name “zigzag emperor”.

Gonimbrasia tyrrhea male

Gonimbrasia tyrrhea is also a notable species, due to their larvae reportedly being prolific defoliators. This seasonal species appears to produce 1 to 2 broods per year; pupae of the moths remain dormant during the dry season, but mass-emergences are triggered by the warm monsoon rains when the wet season begins. Then, the short-lived moths (they have a lifespan of 4-7 days) begin to mate, and females deposit eggs on the host plant.

Larvae of Gonimbrasia tyrrhea can be rather abundant – so abundant they can strip all the leaves from a tree! Reportedly the larvae are found on several species of Acacia (Leguminosae), Uapaca (Phyllanthaceae), Ozoroa concolor  (Anacardiaceae), Pinus (Pinaceae), Diospyros (Ebanaceae), Salix (Saliaceae), Populus (Saliaceae) and more. In captivity they feed on many plants [including several non-native ones too] such as Liquidambar (Altingiaceae), Prunus (Rosaceae), and Quercus (Fagaceae).

In literature, the species is often referred to as a pest. And while it is undeniable that the huge amounts of larvae can be detrimental to the local vegetation, consider the flip side; defoliators have an important role to fill in the environment too, especially in their native habitat. Insectivores such as bats and birds may rely on the seasonal abundance of insects to feed their offspring – being especially reliant on overabundant caterpillar or moth species. Life sustains life, and by no means do moth species degrade the environments on which they, themselves, depend on for their survival. As usual there is a human factor in the equation. Species can overpopulate due to a lack of natural enemies (when the environment is degraded by humans), or due to an overabundance of resources (when the environment is degraded by humans) – deforestation for example tends to greatly reduce the diversity of the vegetation. Or how about our tendency to create monocultures? Since not all species can thrive in degraded habitats.

Don’t get me wrong – several scientific publications state it loudly – Gonimbrasia tyrrhea is a ‘pest’. That doesn’t mean however, that their presence is harmful to the environment in every scenario. It mostly just means their presence is inconvenient to humans. Yes, invasive species and pests can be harmful to the environment too (Lymantria dispar, anyone?). But in this case, we are speaking of a native insect, in it’s native environment. There is no doubt that Gonimbrasia tyrrhea makes a positive contribution to the environment as well, by managing the vegetation, and providing a source of proteïn for insectivorous animals. For example, did you know cattle egrets consume large amounts of Gonimbrasia tyrrhea caterpillars?

That being said, there are reports of the larvae feeding on food crops, although reliable sources on this are a bit scarce – some literature mentions they can damage apple trees (Malus) and trees such as pine tree (Pinus) that could be economically important as hardwood. Interestingly, studies quantifying the damage they do as pests are scarcer than the amount of sources willing to label them pests. Am I oddly defensive about this species being a pest? Maybe. But there is a trend in entomology in which publications are quick to label any species that is either a defoliator, or a species that can feed on economically important crops, a pest, without quantifying the damage, or their other important roles in the environment. And the issue with that is that we are quick to manage insect species branded as pests, while missing the bigger picture; especially considering the overabundance of pest species is usually a sign of environmental degradation and thus, a systemic problem (deforestation, mono cultures, climate change, droughts) . When humans alter the landscape, many species lose out and decline – but a small number of species benefit from it, becoming overabundant in the process.

Gonimbrasia tyrrhea larva

The larvae of Gonimbrasia tyrrhea are highly social when they are immature, although the final instar becomes solitary. They are frequently observed feeding in large groups. Their appearance is quite remarkable – they have a black (melanic) cuticle that is covered with pale white (to light blueish) scale like structures that are typical for larvae of the genus Gonimbrasia. They are also covered with very fine bristle-like patches of silvery hair.

Gonimbrasia tyrrhea male
  • Difficulty rating:  Average – the species is somewhat easy to raise. They grow really well on Acacia, oak tree (Quercus) or sweetgum (Liquidambar).
  • Rearing difficulty: 5/10 (From egg to pupa)
  • Pairing difficulty: 6.5/10 (Achieving copulations)
  • Host plants: Larvae of Gonimbrasia tyrrhea can be rather abundant – so abundant they can strip all the leaves from a tree! Reportedly the larvae are found on several species of Acacia (Leguminosae), Uapaca (Phyllanthaceae), Ozoroa concolor  (Anacardiaceae), Pinus (Pinaceae), Diospyros (Ebanaceae), Salix (Saliaceae), Populus (Saliaceae) and more. In captivity they feed on many plants [including several non-native ones too] such as Liquidambar (Altingiaceae), Prunus (Rosaceae), and Quercus (Fagaceae). Clearly this species is very polyphagous and can take advantage of many shrubs and trees, perhaps including many not yet recorded. It would be good to experiment with random woody plants.
  • Natural range: This species is found in Congo, DRCongo, Kenya, Namibia, South Africa, Tanzania, Zambia and Zimbabwe. Generally speaking fund in April-June and reportedly in some locations, there is another breed in December.
  • Polyphagous: yes, very!  
  • Generations:  Seems to have mostly 1-2 generations a year. Mating occurs in the rainy season – larvae pupate and the pupae are dormant in the dry season.
  • Family: Saturniidae (silkmoths)
  • Pupation: Naked pupa (underground)
  • Prefered climate: Sub-tropical Africa
  • Wingspan: 100mm-140mm
  • Binomial name: Gonimbrasia tyrrhea (Cramer, 1775)

Gonimbrasia tyrrhea is not a species I recommend for complete beginners. That being said, if you have basic experience with Saturniidae they are not very hard.

The ‘baby caterpillars’ (young instars) require warmth and a lot of humidity. The fully grown ‘mature caterpillars’ (final instars) require warmth and lower humidity.

This species can eat many plants in captivity! Larvae grow very big and healthy on oak tree (Quercus), willow tree (Salix) and sweetgum (Liquidambar). Some people have also used cherry (Prunus) succesfully. If available, Acacia should also be an excellent choice.

Gonimbrasia tyrrhea hatching from their eggs
L1 Gonimbrasia tyrrhea feed in groups
L2 Gonimbrasia tyrrhea feed in groups
L2 Gonimbrasia tyrrhea feed in groups
Gonimbrasia tyrrhea rearing setup

The first instar of this species, I typically raise them in airtight plastic containers with cuttings of food plant (sometimes placed in water bottles to keep them fresh). Make sure to add ventilation holes and if you can, a layer of moisture absorbing paper towels. Remove excrement every 2 days; replace food plant every 3-4 days with fresh plant.

After the first instar, I recommend a more dry enclosure. Big larvae don’t like the humid air in plastic boxes; they need more ventilation. This allows the container to dry out indoors. Humid plastic boxes tend to work for young larvae that need more humidity; but not beyond the 2nd or 3rd life stage. Place them in a pop-up cage, or big plastic container with the lid removed (replace with netting).

The first two instars (L1, L2) are social and live in groups. The later instars become more solitary (L3, L4, L5) although they are very tolerant of high densities.

Gonimbrasia tyrrhea L3
L3 Gonimbrasia tyrrhea
L4 Gonimbrasia tyrrhea
Gonimbrasia tyrrhea eating
L4 and L5 Gonimbrasia tyrrhea
L5 (and some L4) Gonimbrasia tyrrhea
Fully grown (L5) Gonimbrasia tyrrhea
Gonimbrasia tyrrhea rearing setup – yes, the owner of this website has no breeding secrets! Copy my methods. I chose to use a large plastic container, with a generous layer of paper towels on the bottom (to absorb moisture and to make it easier to clean). Then, I cut branches of food plant (in this case Liquidambar or sweetgum) and I stuck them in empty bottles and cans. This keeps the leaves fresh; think of flowers in a vase!

The third, fourth and fifth instar can be raised in a similar setup. Personally, I chose to use a large plastic container, with a generous layer of paper towels on the bottom (to absorb moisture and to make it easier to clean). Then, I cut branches of food plant (in this case Liquidambar or sweetgum) and I stuck them in empty bottles and cans. This keeps the leaves fresh; think of flowers in a vase!

On the lid of the box, I cut a huge hole for ventilation. Between the lid of box, I trapped a large piece of netting to prevent larvae from escaping.

From instar 3 and beyond the larvae are very pale; their skin (cuticle) is purely black, but coated with scale-like structures that are white and blueish.

In instar 4 and instar 5, larvae may also have subtle blotches of red on their sides. They also have brushes of fine, scruffy, silvery hair coating their bodies.

When the larvae are fully grown they can grow quite large (up to 8-9cm!). When they are fully grown, they do not spin cocoons – instead they will drop to the floor and start wandering aimlessly. After that they will burrow underground, and create a cavity in the soil in which they pupate! The larvae of this silkmoth pupate underground.

In captivity, you can use moist paper towels, or soil substrate to successfully allow the larvae to pupate.

Gonimbrasia tyrrhea pupating
Gonimbrasia tyrrhea pupae
I keep the pupae in humid vermiculite

Congratulations! The pupae can easily be stored in humid substrate that does not grow moldy. I prefer to use vermiculite. For the pupae, it could be worth it to try and simulate the African dry season / wet season – perhaps it would result in the moths eclosing more predictably! In east Africa, typically the dry season runs from May to September, with June and July relatively cool and August and September hot and humid. The (warm!) wet season begins in November and finishes in March. April is autumn and a transition month while late September to early November is spring. Note; this is a generalization (it can very per country).

This seasonal species appears to produce 1 to 2 broods per year; pupae of the moths remain dormant during the dry season, but mass-emergences are triggered by the warm monsoon rains when the wet season begins. Then, the short-lived moths (they have a lifespan of 4-7 days) begin to mate, and females deposit eggs on the host plant.

Males and females look quite similar, but males are smaller and have much larger feathered antennae.

Note: all specimens on this page are males (a picture of a female and perhaps a mating will be added ASAP).

Gonimbrasia tyrrhea (male)
Gonimbrasia tyrrhea (male)
Gonimbrasia tyrrhea (male)
Gonimbrasia tyrrhea (male)

Keep them warm and humid between April and June – that helps. Keep them more dry and cool between June and April. That being said, in captivity the moths can be confused and sometimes emerge rather sporadically and unexpectedly. Gonimbrasia can sometimes be tricky to synchronize.

Congratulations! The moths are breathtakingly beautiful with their furry olive grey/green wings, and purple hind wings with eye spot markings on them.

This species is short lived for a moth this size (4-7 days). Females live longer.

After mating, females quickly lay most of their eggs in 1-2 days time (sometimes they dump all of them in one spot!). Both males and females pass away pretty quickly after mating. Generally speaking fund in April-June and reportedly in some locations, there is another breed in December.

Males and females prefer warmer nights, in undisturbed (no artificial light) darkness.

 

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Citations: Coppens, B. (2022); Written by Bart Coppens; based on a real life breeding experience [for citations in literature and publications] 

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