REARING SILKMOTHS (Saturniidae)

For many people in Europe an interest in Giant Silkmoths comes from seeing a picture of a silkmoth in a book, rearing some larvae at school or seeing a live insect at a tropical Butterfly House. No matter how you first acquired an interest is irrelevant,it's the fact that this stunning insect captured your imagination and lead to an active desire to learn more and hopefully get some hands on experience with these wonderful creatures!

Today through worldwide captive breeding programmes a large variety of silkmoths are available to the home breeder. For species that come from breeding Farms oversea, particularly in poorer parts of the world the programmes are providing much needed revenue for needy people. In turn those of us in the richer parts of the world enjoy an interchange of mutual fascination by means of the Giant Silkmoths. Apart from rearing of livestock (which is not practical with all people) a reference collection can be produced of "SET" (dried and preserved) specimens. Rather than look upon such collections as macabre they make up much needed vaults of information which is unattainable from any other source. Photography also plays a growing role and is particularly useful for showing silkmoths at various stages of development and showing the natural posture of live insects which is lost in "SET" specimen collections. Whatever your choice there is a place for all aspects of lepidoptera and Entomological study through whichever media one prefers so long as a moral code of practice and common sense is followed. So be happy and enjoy Giant Silkmoths the worlds largest moths!

Classification

Giant silkmoths belong to the family of Saturniidae. In order to understand classification here is an example. This would be the classification through to the Giant Atlas Silkmoth (A.atlas)

1. Kingdom: Animalia
2. Phylum: Arthropoda
3. Class: Insecta
4. Order: Lepidoptera
5. Family: Saturniidae
6. Subfamily: Saturniinae
7. Tribe: Saturniini
8. Genus: Attacus
9. Species: atalas

LIFECYCLE

OVA (Eggs)

Silkmoth eggs vary in size from quite small to some of the largest of any living Lepidoptera (Butterfly/Moth) Ova are generally quite strong but should still be handled as little as possible to avoid damage. They are best kept in a small plastic container lined on the base with tissue. When the larvae hatch the tissue will provide a foothold and aid emergence. Tissue also prevents excessive moisture occuring and prevents ova rolling around. Ova breath through a tiny hole in one end known as the micropyle. Although excessive moisture can be harmful the ova still need some moisture to prevent them from drying out especially if from tropical humid areas. The easiest way is to lift the lid and simply "breath" on the ova. The moisture in your breath will give adequate water vapour and also lifting the lid will provide fresh oxygen. So long as you lift the lid daily no air holes need to be made in the container. Make sure ova are not in direct sunlight and away from artificial heat otherwise too much heat will kill them. Some breeders add a little "Spot" of water to the tissue to help provide moisture, but if you do this kep an eye out for condensation and any fungal growth. Remove any fungus that grows or eggs that collapse (these are generally infertile) Under no circumstances add leaves/foodplant on the hunch that it will give the larvae quick access to the foodplant. Instead any foodplant present will give off gases which quickly kill the ova, so never add foodplant. Rather wait and remove small larvae with a fine paint brush after they hatch to a container with foodplant. Hatching time varies between species, but generally 2-3 weeks from laying is about right. Some soecies (leopa/Dictyoploca) overwinter as ova and these should be kept cold in a refrigerator until Spring.

LARVAE (Caterpillars)

The fun begins in earnest when the tiny larvae hatch. Make sure you allow time for small larvae to eat their egg shell (if they want to) as it can be a necessary prelude to starting on foliage. When you are happy the larvae are ready to move (a few hours is ample) use a soft fine paint brush to gently lift the larvae into a small container with foodpalnt (10 larvae in say 79x47x22mm). Never force the larvae from their footing as it is easy to damage the legs and body. Patience is required to move them safely. Line the container base with tissue paper which again acts to subdue condensation and also aids cleaning boxes out. Some species are reluctant to start feeding. Make sure the foodplant is touching all side of the container. Never just lay leaves on the base as the larvae will simply tend to walk around them. Once the larvae have started feeding they generally don't stop! Remember silkmoth larvae consume vast amounts of foodplant so have plenty on hand! For young larvae choose neither old nor new leaves but what is the norm. Care of the growing larvae is straight forward. Rear the small larvae in plastic boxes such as sandwich tubs (clear types are available commercially for insects) While some species are gregarious (stay together) most larvae are solitary so be sure not to overcrowd tubs as it can cause distress, disease and inevitably death. in order for larvae to grow they will have to moult (ecdysis) during moulting the larvae become immobile and stop feeding. Do not mistake this for sickness, it is a natural part of growth. Look out for these simple changes. The larva attaches itself to a twig/leaf by means of a fine silk layer. Then the head tends to look very small in comparison to the body. Then the skin on the heads "Splits" and slowly the new soft larvae works it's way out of the old skin (which some species eat!) After moulting the larva's body is quite soft so should not be touched until the new skin hardens. This "Skin-changing" (ecdysis) will occur four times before the larva is full grown and ready for pupation. Each change is called an "instar" When the larvae have reached their second instar it is best to move then to larger more ventilated containers. Various types are used but the essential ingrediant is hygiene and ventilation. In our rearing we use all net or net and part wood cages of simple construction. This allows air to circulate and prevents excessive moisture. Moisture/condensation can quickly cause larvae to have intestinal problems such as liquid frass (droppings) and lethargy. This infection if viral can quickly spread and kill all your larvae so always plan to move larvae to larger net cages a.s.a.p. Even here check regularly for any larvae showing signs of sickness and remove them/it from the rest. Never put wet, damp or soiled (roadside contamination) in with your larvae as again this can cuse intestinal problems. Another advantage in using net cages is that you can use cut foliage which can be stood in a jar/milk bottle. Make sure you plug up the excess around the neck of the bottle with cotton wool to avoid any larvae drowning. Heat plays a part in the success of rearing tropical species ans some require a little more humidity than others. Generally speaking if you are rearing through the summmer or in a central heated house the temperature tends to be adequate for most species. Hygiene cannot be overstated as a batch of larvae can be OK one minuet then all dead the next through simple neglect of hygiene. Clean out the frass from cages regular,certainly every time you change the foodplant. Continue to use tissue or newspaper in the larger cages as a base lining for easy cleaning and hygiene. Never use detergents directly. If you wish to disinfect use hot water (some iodine or washing soda) and rinse & dry thoroughly before re-use. As an alternative to cages some species (especially European/North american species) can be "Sleeved" outside on growing foodplant. The idea is to make a tubular shape net - much like a stocking. Slide the net over the chosen branch or plant. Tie one end securely then add the larvae and tie the other end. In this way the larvae can be left to feed at leisure and cleaning out is less frequent. With sleeved larvae they obtain 100% living foliage to feed on. The set back for this method in the case of Giant Silkmoths if your in the UK or Northern Europe is the weather! Excessive rain or cold spells can cause disaster but it is a useful alternative if all conditions are good. If you do decide to sleeve out doors always use very fine netting as parastic wasps and other predetors will endeavour to get in and use your larvae as hosts for their own or a quick meal ticket!

PUPATION

This is the time when a full grown larva begins its amazing journey of metamorphosis into the moth it will become. Full grown larvae will stop feeding and empty their guts of waist in the form of a slushy dropping (frass). Do not mistake this for disease it is the normal stage of events prior to pupation. After this the larvae may wander for some time aimlessly before deciding on a place to pupate. In the case of Silkmoths each species/family has its own method of pupation. Some species will spin leaves together and make their cocoon between leaves. Others will build a silk cocoon around themselves suspended from a silk line. For still others pupation is subterranean. Wheras those spinning silk cocoons amongst foliage tend to just get on with it, those with a subterranean need will require help. As soon as you see the larvae show the tell tail signs, (stop feeding,emptying of gut,colour change & wandering) then take the larvae from the cage and place in a deep plastic container filled about half way with sterile peat. Ensure the substrate is not wet and not too dry,just damp. The larva will wander on the surface for some time digging itself in then out the soil. Eventually it will settle,disappear and change into its pupal form. Do not overcrowd boxes with lots of larvae as they will disturb each other underground. During pupation whether in a silk cocoon or underground never disturb the larva during it's transformation to pupa. After about 7-14 days remove the spun cocoon or paupae and pepare them for either hibernation (if it's late autumn/fall) or for the next generation.

EMERGENCE

Hatching cocoons or puape is pretty straight forward. Temperature should be warm but not roasting. Normal central heating should suffice. Simply lay out the cocoons on the base of the mergence cage. Some breeders pin the cocoons to the side of the netting cages via a strand of silk. Pupae without cocoons are best placed on or just below the surface of a tray containing damp peat. The peat helps them get a foothold during emergence. Lightly spray the cocoons twice daily, but do not saturate as mould could form inside and kill the pupa. If you are nearing autumn/fall and it is unlikely you will be able to raise a second brood then adults can be used as "SET" specimens, or cocoons can be put into winter hibernation and brought out in spring for hatching. This hibernation period is called diapause. Hibernating pupae/cocoons can be laid in plastic boxes with cotton wool for padding and housed in the refrigerator. An outside garage or shed is also fine son long as the tempertaure does stays low (but not freezing!) In some species diapause is laight induced/broken while in others it is temperature/humidity that breaks the "sleep" and starts the process of hatching off. Always check pupae/cocoons during hibernation for any that appear light of have gone squishy as they will probably be dead and need removing so they do not contaminate others. In Spring bring out the pupae/cocoons when you see the buds on the trees beginning to break on the trees in order to get an early start. To avoid crippled moths emerging some breeders will enlarge the emergence hole in the silk cocoon so as to make the moths exit easier. Do this very carefully so you do not damage the pupae inside. Once the moth (imago) has emerged do not disturb it but allow it to dry its wings fully before attempting to move it. Use if possible all net cages in the emergence procedure.

ADULT SILKMOTHS

This is the stage when you can admire the beauty of the insect and the amazing life cyclye you have played a role in. Unlike Butterflies and many moths, Silkmoths do not feed. They have no mouth parts and simply use the energy they have stored from the larval stage to carry out their one function, that of reproduction. If you intend breeding the silkmoths you have you will need to prepare a pairing cage. Normally these are made of netting and vary in size depending on the size of the moths. Each species has its own needs depending on its origin and some are easier than others. The recommended sizes for pairing are 1) Smaller moths = 30cm diameter net cage. 2) Larger moths 60cm diameter net cage. The drop/length of the cage again vary from 30-60cm. Most cages used are of all net manufacture with a zip to allow easy access to the pairing cage. (some breeders dedicate a whole room to specie ssuch as A.atlas) Once you have a male and female emerged put them into the pairing cage. You can add more but overcrowding is not recommended as the males not paired can interfere with already coupled moths. Males begin flight around 10pm but it does vary between species (some even being day flying and requiring sunshine!) Females tend to begin "calling" (release of pheromone) on the second night of emergence. It is essential that you have a pair emerge close togeather as any gap between the emergence of the male and female can mean no pairings are made. This is because the male tends to wear himself out very quickly hunting  for the elusive female. You can slow this energy loss down by putting the male into a cool & light part of the house until the female emerges. This period can be one of the most frustrating especially if you are low on cocoons/pupae (ideally 10 or more will give you more chance of a male and female hatching at the same time) If the moths refuse to fly then added heat and humidity can be used to help them get started. A shower room is a perfect location as it produces plenty of humidity, but heat will also be required. When pairing is finally acheived in most species they stay tied for most of the following day. However in other species the pairing is very breif and not witnessed (unless you stay up all night!) After pairing the female lays almost immediately. Eggs are glued around the cage over the course of a few nights. The males may mate again with other fresh females,but will not last much longer than 4-6 days. The females too once finished egg laying (ovipositing) will die. Some breeders remove females that are known to have paired and place them in a card box so the eggs can be laid and gathered more easily. Once you have colllected up the fertile ova then you task begins all over again!

CONCLUSION

This is just the very basic knowledge required to begin rearing Giant silkmoths. With experience and practise you will master techniques and maybe invent ones. Each species you breed is unique and some require more specialist care. Whatever the case your joy will be great as you become closer to these magnificent insects.

By Jason Wright (entomologist)

SILKMOTH SPECIES YOU MAY WANT TO TRY...

1. American Moon (A.luna) Foodplants Birch/Walnut/Liquidamber
2. Bulls Eye (A.io) Foodplants Plum/Lime
3. Caletta Silkmoth (E.calleta) Foodplants Privet/Cherry/Plum
4. Camphor silkmoth (C.japonica) Foodplants Oak/Chestnut/Willow/Apple/Hawthorn
5. Ceanothus Silkmoth (H.euryalis) Apple/Plum/Sallow/Willow
6. Chinese Oak (A.pernyi) One of the best beginners species. Foodplants Oak/Hornbeam/Chestnut/Plum/Apple
7. Columbus Silkmoth (H.columbia) Foodplants elaeagnus angustifolia/Willow
8. Comet Moth (A.mittrei) Foodplant Sumach
9. Emperor Gum (A.eucalypti) Foodplant Eucalyptus
10. Emperor Silkmoth (S.pavonia) Foodplants Bramble/Heather/Blackthorn/Hawthorn
11. Giant Atlas (A.atlas) Fp. Privet/Willow/Lilac
12. Giant Atlas (A.ceaser) Fp. Privet/Willow
13. Golden Emperor (L.katinka) Fp. Grape Vine/Virginia creeper
14. Glovers Silkmoth (H.golveri) Fp. Willow/Sallow/Apple/Plum
15. Great Peocock (S.pyri) Fp. Walnut/Apple/Plum/Ash/Poplar/Oak
16. Himalayan Oak Silkmoth (A.roylei) Fp. Oak 
17. Horned Devil (C.regalis) Fp. Sumach/Walnut/Liquidamber
18. Indian Moon (A.selene) Fp.Rhododendron/Lilac/Hawthorn/Apple/Plum
19. Japanese Moon (A.gnoma) Fp. Alder/liquidamber
20. Japanese Oak Silkmoth (A.yamamai) Fp. Oak
21. Jonasi Silkmoth (C.jonasi) Fp. Oak/Chestnut/Willow/Apple/Hawthorn
22. Leucanella Silkmoth (L.memusae) Fp. Privet/lilac
23. Madagascan Moon (A.maenas) Fp. Sweet Chestnut/Oak/Cherry
24. Madagascan Bulls Eye (A.suraka) Fp. Privet
25. Naranja Bulls Eye (A.naranja) Fp. Privet/Willow
26. Pallid Emperor (C.forda) Fp. Birch/Apple/Plum
27. Polyphemus Silkmoth (A.polyphemus) Fp. Hawthorn/Apple/Oak
28. Robin Silkmoth (H.cecropia) Fp. Plum/Apple/Willow/Birch
29. Rothchilds Atlas (R.jacobeae) Fp. Privet/Lilac/Oak
30. Rothchilds Atlas (R.lebeau) Fp. Privet/Lilac/Oak
31. Spanish Moon (G.isabellae) Fp. Scots Pine
32. Spice Bush (C.promethea) Fp. Tulip Tree/Birch/Ash/Liquidamber/Lilac
33. Tau Emperor (A.tau) Fp. Lime/Oak/Birch/Sycamore
34. Thai Golden Emperor (L.diversiocellta) Grape Vine/Virginia creeper
35. Tree of Heaven (S.cynthia ricini) Fp. Privet/Laburnum/Whitebeam/Rowan/Lilac
36. Tulip Tree Silkmoth (C.angulifera)Fp. Tulip Tree/Magnolia tripetala/Prunus serotina
37. Tusseh Silkmoth (A.mylitta) Fp. Oak 
38. Zambesina Emperor (G.zambesina) Fp. Beech
39. Zig Zag Emperor (G.tyrrhea) Fp. Apple/Hawthorn

Many more species become available, these are some I breed. Have Fun - themothman

For more information visit the Lepidoptera Breeders Association.