Graellsia isabellae — “Spanish moon moth”

Welcome on my page about how to rear and breed Graellsia isabellae.

Graellsia isabellae, the Spanish moon moth,  is a marvelous insect that is endemic to the mountainous regions in the Alps and Pyrenees in Spain, France, and Switzerland, though in the latter country has been speculated to be an introduction.

graellsia isabellae bartThree freshly emerged males resting on a stick in captivity. One has already torn a wing, males of this species are very frantic and active.

  • Difficulty rating:  Challenging (Not extremely hard, succesful rearing and pairing can never be taken for granted. For experienced breeders)
  • Rearing difficulty: 6.5/10 (From egg to pupa)
  • Pairing difficulty: 8.5/10 (Archieving copulations)
  • Host plants: Pinus sp. 
  •  Natural range:  Europe, the Alps and Pyrenees of Spain, France, very small parts of Italy and introduced by humans in Zwitserland
  • Polyphagous:   Yes, but only on coniferous trees – Pinus sp. preferred 
  • Generations: Univoltine  (only one generation a year, cocoons always overwinter)
  • Family: Saturniidae (silkmoths)
  • Pupation:  Cocoons (silk encasing)
  • Prefered climate: Temperate (Dry, with warm to hot days followed by cold nights. High altitude mountain pine forest). Tolerates both heat and cold very well, but is sensitive to too high humidity
  • Special notes: The biggest problem with this species in captivity are moths that have no interest in pairing. This could be because of inbreeding (inbred moths typically have no interest in pairing with their siblings, since their pheromones are similar) and because of low vitality of captive livestock because they are reared in suboptimal conditions. Wild stock is the best, but even those individuals can be hard to pair.
  • Wingspan: 60 – 100mm (medium) 

Graellsia isabellae is a pine tree feeder, and I recommend using Pinus sylvestris over any other kind of coniferous trees, as it is the native host plant. Pinus strobus is another viable second choice, and thirdly, though not optimal, it may accept fir or spruce such as Pseudotsuga, Tsuga, or Picea. The moths live in high altitude pine forests. Though the habitat may reasonably heat up during the day, which are rocky and dry pine forests, at night and in winter the species is also subjugated to rather harsh cold, due to the high altitude. Moths, after spending the winter as diapausing pupae inside their cocoons, emerge in early summer, from May to early July, after which they reproduce, and leave the next generation of larvae to feed on pine trees. Cocoons will always overwinter until the next spring, as this species has only one generation a year.

The larvae, with stunning lime green camouflage, develop reasonably well in plastic boxes. They must be kept clean and dry, they are not fond of high humidity. It is also better to rear them in low density, and not include too much larvae per rearing box. They are best left alone and undisturbed, on room temperature. They can also be sleeved outside on pine tree, but avoid cold and wet periods.

graellsia cat.jpg                       Final instar larva of Graellsia isabellae

After going through five instars, fully grown larvae will spin a cocoon, which will emerge the next year. It must be kept cold during the winter.  For spinning, they can be offered moss or other substrate, which they will readily use.

cocoonsss.jpgGraellsia isabellae cocoons

Graellsia isabellae is a relict species. It is the most primitive moon moth, and a remnant from the past, that has been isolated in a relatively unchanged habitat. Graellsia isabellae shares an ancestor with other moon moths  that split off into the more modern genera Actias and Argema. Pairings can be difficult to archieve, and in captivity a part of the males seem disinterested in pairing alltogether, atleast from my observation, or somehow failed to locate the females.

Handpairing is difficult but archievable, and is recommended for experienced breeders, having a higher succes rate than getting the harder to archieve natural pairing.

Graellsia isa.jpgGraellsia isabellae male

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The aim of this website is to provide information about many species of moths and butterflies around the world, with a slight focus on rearing them in captivity.

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