Grellada imitans

Grellada imitans by Robin Allen

Robin is a very talented moth breeder from the United Kingdom; I’m always very pleased to see his experience on social media. He has bred various species that I always struggled with for years. Today, Robin shared with me the breeding of an African Lappet moth: “Grellada imitans”. Thank you Robin! 

Grellada imitans is a large Lasiocampid moth from Africa. I obtained eggs of this species from the inimitable Andrew Spicer in the UK through his contact with Lucien Mballa in Obout Village, Cameroon and their work on the Cameroon Ark project. One female was captured, and laid eggs.

When the eggs arrived, we were still unsure of the species. Perhaps it was going to be Pachyna subfascia. Perhaps Pallastica mesoleuca. Or perhaps some other relative of these species. Not much is known about many African species, so it would be intriguing to find out what these were.

The eggs were large, round, pale brown mottled with darker brown. They were kept like many other eggs: in a closed sealed container, with occasional humidity from breath on the inside of the lid. These eggs had already travelled from Cameroon to the UK, and travelled again within the UK, so it was not long before these eggs hatched on the 22nd April.

Like many Lasiocampids, the young larvae had a line of long hairs along each side. These were longer around the front segments. The mid section of the body was striped white, yellow and black.

At first, the larvae did not seem keen to feed on any foodplant. Many plants were offered, with no sign of interest. Perhaps the larvae were confused or just needed to spend some time exploring, but eventually they settled for Paulownia leaves. I expect they would have happily settled on many other plants, but Paulownia was a good choice as I have an infinite supply available.

After a few days, the larvae were into the second instar. At this stage, the larvae developed two red stripes on the back of the thoracic segments behind the head, as well as a more intricate patterning along the back.

By 5th May, some of the L2 larvae were reaching L3 instar. At this stage, the larvae became more hairy, starting to develop a more cryptic camouflage.

At 22 days old, the L4 instar brought with it much greater camouflage, with the long side hairs now able to blend into any surface.

The larvae would often rest on tissue which was used to improve cleanliness. I presume that they detected the woody fibres and texture of the tissue as resembling tree bark. For this reason, it is advisable to place a network of sticks across the bottom of the cage. This provides places for the larvae to take up their natural resting positions, without spending time in amongst their frass. Tissue should be avoided, as it encourages the larvae to return to the floor, where health is at risk.

At the L5 instar, the larvae started to develop small black spines criss-crossing along their back amongst the finer hairs.

The red stripes behind the head, up until now being not very concerning, also became much more advanced; each contained two ‘christmas trees’ of red spines. When threatened, the larvae would evert these spine organs outward, providing a striking visual display. Any predator would instantly reconsider an attack.

Sometimes, when disturbed, the larvae would whip their frontal segments side-to-side at high speed. This created a fast drumming vibration as well as a visual display drawing attention to their red spines.

By 7th June (46 days), the larvae gave a reminder of how slow growing Lasiocampids can be. L5 was not the end. These were moulting to L6, and setting in for the long haul.

At this time, some larvae exhibited an even more advanced defensive behaviour. If threatened, they would raise up the front half of their body off the ground, in a shape like a Cobra. They would strike backwards or sideways with their red spines everted, whipping their body around to make contact wherever they felt the touch of an attacker.

These larvae were incredibly variable in their colour forms. Although the basic pattern always remained the same, many different colours were seen; from almost pure white, through to shades of green, brown, and even some hints of purple or maroon.

In the latter instars, the larvae enjoyed hiding on bark / stems during daylight hours, only feeding during the night. I expect if one were to extend the night-time hours and shorten the day length, these larvae would grow faster. Half of their time is spent resting motionless during the day; this must have great value against predators in the wild, but perhaps serves no purpose in captivity.

The camouflage of these larvae is helped by the structure of the ‘hairs’. These modified structures have flattenned areas which lay flat and break up the lines of hairs, creating a perfect match for lichens and tree barks.

Despite their spines and their behaviours, these larvae were easy to raise and welcomed handling. They were keen to explore new objects, be they sticks, leaves, or human fingers. Their spines were not a worry. They grew to an impressive size, as much as 12cm when relaxed, and perhaps up to 15cm when reaching out at full stretch.

Thankfully, L6 was the last instar. 60 days after the eggs hatched, the first cocoons were being formed in late June. The first to pupate were the males, with some females taking many days longer to reach full size. Handling the cocoons was the first time that the spines became a real problem. I would recommend just leaving the cocoons alone! But, while these spines would readily piece the skin, the reaction was not intense. Handling a dozen cocoons would fill fingers with spines, but a wash under cold water would easily break away the loose ends of the spines and wash them away. They did not cause any allergic reaction, but those who do know they are allergic to other species should exercise caution.

Pupae were an interesting shape, and just like the larvae they had a good head of hair!

Below: Male left, female right (because females are always right!)

Of course, the first to emerge were some of the quite small males. These had excellent camouflage as a chip of wood, and would easily disappear on the right colour of bark. The claspers were peculiarly adapted to form part of this camouflage.

When disturbed, the males immediate reaction was often to drop to the ground, closing their wings and legs as tightly as possible. This gave the impression of a piece of wood / bark / dead leaf, and would be impossible to detect in leaf litter. Some would even rotate their head 90 degrees around to the side, which made normally symmetrical features of eyes and antennae difficult to recognise.

If disturbed further, the moth would invert its wings behind its back and feign death. This would also combine with a purple and green iridescence on the underside of the forewings and hindwings, perhaps giving an impression of a rotting deceased corpse. The male would also open his claspers wide.

The female of the species was much heavier and larger than the male. Another thing to notice with this species, was the incredible strength of the tarsal claws, especially of the female.

When upset, the female would display wasp-like markings on her hairy abdomen. She would also push her ovipositor at the attacker, perhaps mimicking a stinging insect. Of course, this was accompanied by the usual release of fluids, but in nowhere near the quantity of the infamous Argema mittrei.

The sexual dimorphism is striking when the male and female are seen side by side. An early naturalist could easily be excused for believing these were two completely unrelated species, with such drastic differences in body size, shape, weight and wing pattern.

By the time the females were emerging, many of the males had damaged their wings. The males are short-lived, so a good recommendation would be to cool the male pupae with an aim to delay them by a few days to better coincide with emergence of the females.

Pairing was achieved on the first night in a small 30x30x30cm cage containing two females and several males, on a cool summer’s night at 16 deg C, even despite rainy weather. Pairing seemed quite easy to achieve.

Egg laying commenced the next night, with around 200 eggs being oviposited in a single night. The eggs were laid in circular clusters approximately 1 inch across, on cage netting.

The next generation of eggs took only 12 days to hatch (at indoor room temperature). I found common Ivy (Hedera helix) to be loved by the young caterpillars.
Rearing this moth was thoroughly enjoyable, in part because the larvae were very predictable and easy to raise. Their day-time sleep and night-time feed pattern meant that it was easy to predict how much fuel they would need for the night ahead.

Environmental conditions in my rearing were far from the perfect ideal needed by some less resilient species. Plastic boxes with relatively low ventilation caused no ill effects. Even when condensation built up enough to cause matting of their hair, the larvae thrived in damp conditions just as well as in the dry. With a matrix of sticks across the bottom of the cage, the larvae were not hampered by frass on the bottom of their container, allowing a great degree of laziness in cleaning their enclosure. Apart from a very small number of losses in the earliest instars, the larvae seemed virtually indestructible once they were half grown.

Other than the spiny cocoons, they were easy to handle at all stages. Larvae were explorative and ‘friendly’, rather than those which drop to the floor at the slightest disturbance or spit out the contents of their guts or refuse to move. Adult males that pretend to be dead are far easier to move from cage to cage than the flighty insanity of Actias isis or the flappy nonsense of Antheraea species. Females would dislike being moved, but once their claws were de-tangled from netting they were relaxed and calm to handle. I would certainly recommend!

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