Plastic Rearing Containers. If you receive eggs through the post, transfer them immediately into one of the small plastic rearing containers. Don't use a paper lining and never add foodplant to eggs in a box. Keep away from sunlight. As the larvae hatch, give them time to eat some of their egg-shells and when they have wandered away, coax them gently on to the end of an artist's paintbrush which can then be used to transfer the larvae to a larger plastic rearing container, lined with absorbent paper and with a sprig of freshly gathered foodplant. Loose leaves don't keep well, use a sprig with both stem and leaf. If larvae are reluctant to feed, keep them in a small box, tightly confined with the foodplant so they cannot stray from it, then they will usually start to feed.

Plastic Rearing Containers are suitable for young larvae, before they are large enough to cage or sleeve. There should be an absorbent paper lining to the larvae box. Foodplant must be very fresh and changed every day, together with the paper lining. Don't try to pull larvae off a leaf or stem, just cut the plant round the larva and put on a fresh lining with the new food each day. Put the fresh foodplant on top of the older food with larvae on. The larvae will make their way up to fresh food, better than downward. Don't allow the box to be in sunlight, and don't think a missed day for cleaning out won't matter. Absolute cleanliness is essential. The closed container keeps the foodplant fresh. No holes are needed because there is more than enough trapped air for larvae to breathe. Never allow excessive condensation, nor mould. The size of box should be chosen according to the size and number of larvae being reared. Crowding larvae (unless they are gregarious) can be a cause of disease. Although it is best to rear young larvae on fresh growing foodplant, if healthy conditions are maintained in plastic boxes, this method of rearing is often very successful, convenient and protective for the larvae. Larger larvae can be caged on cut foodplant in a jar or water. See the range of cages on this website. If you have growing foodplants and suitable temperature, then larvae can be sleeved on the foodplant, which ensures that foodplant is fresh and reduces time caring for them. Please see the Sleeve section of the WWB website.

For storing winter pupae use a closed plastic box, no ventilation and no padding, just keep the pupae loose in the box. Remove them a month before you wish to incubate the pupae. For the right conditions in the emerging cage, please see the notes for the Pupae Nest, on this website.

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The Pupae Nest, using sheets of bobble foam, is the innovative method used by WWB to keep subterranean pupae, in particular, and other pupae and cocoons in ideal conditions in the emerging cage.

•  Developed specifically for underground pupae: also ideal for cocoons and unattached pupae.

•   Immediate access to pupae for inspection, without disturbance.

•  Provides healthy and moist conditions.

•  Easy observation of pupae that are forming up prior to emergence. 

•  Allows the breeder to anticipate the emergence of required males or females.

•  Ensures hygiene and avoidance of harmful bacteria.

This method has proved to be better than using soil or compost, because it enables instant inspection whenever required, for removal of empty pupal shells or any dead pupae, and to be able clean up, with minimum disturbance of the pupae. The pupae rest in the depressions, in natural conditions of humidity and hygiene.  If they were on plain foam sheets they would roll around, and would be less able to benefit from the humidity assisted by the depressions, which also provide separation. The covering sheet of foam is placed with the bobble side down,  so both of the indented  sides are together, which allows some airflow and eases the passage for adults to emerge and climb to dry their wings.

The pupae and foam should be sprayed thoroughly (not just misted) every day, or more often in higher temperatures. If already moist when you next come to spray, you can reduce or omit further spraying. The pupae and foam should be sprayed thoroughly (not just misted) every day, or more often in higher temperatures. If already very moist when you next come to spray, you can reduce or omit that day's spraying. The base of the upper tray is perforated to allow drainage. It rests in an unperforated tray with a block to separate the two trays and receive the drained water. This drainage allows liberal watering, without risk of the pupae lying in water.  

Cocoons also do well resting on a bobble foam sheet, usually without another sheet covering them, though in exceptionally hot conditions, a moist foam sheet on top of the cocoons, helps to maintain humidity. Cocoons require very liberal watering, not a just a fine mist. Soak them thoroughly, safe in the knowledge that they are well drained.

Butterfly pupae, which in the wild are not formed underground, are usually fixed to a twig or other surface, either hanging from the tail cremaster, or (dependent on their family) upright and held in place by a silken girdle. You can go to the trouble of emulating this artificially (the way to suspend pupae is described in the Exotic Butterfly Pupae section) or they can be laid on the surface of the foam and not covered. As long as they are misted to avoid them drying out, the butterfly usually forms successfully in such pupae laid on foam, and the porous surface helps give the emerging butterfly the grip needed to pull itself out of the chrysalis shell, and crawl to the netting wall of the cage to expand and dry its wings.

From time to time, it is good practice to remove the pupae, wash the foam thoroughly, spray with dilute bleach (about 10% solution, which is not harmful to the pupae) then replace the pupae on nice wet foam. In summer the foam is normally washed about every 2- 3 weeks, using hot water with a touch of bleach added, but without soap or detergent which would create problems with froth and would take too long to rinse away. The washing interval depends on the extent of hatching activity and temperature. Any hint of smell, or slippery feel to the pupae, indicates bacteria, and means that washing is overdue. When adults emerge from the pupa, a waste product Meconium, is ejected. This is only harmful if left so long that it spoils the freshness and encourages bacteria. Empty pupal shells and any other organic matter, are best frequently removed, to avoid build-up of mould or bacteria. In the emerging cage, pupae that are crowded together can develop a slime, caused by bacteria, which slows development and can kill pupae. Pupae nests help to eliminate such risk and periodic washing gives maximum hygiene.

When washing the foam sheets, it is also important to wash and disinfect the two trays. If you are incubating quite a lot of pupae it makes it more convenient to have two Pupae Nests, so you can move the pupae straight into a prepared clean Nest. To encourage this, there is a price reduction for two nests bought together.

TO INCUBATE pupae and COCOONS  An emerging cage should have netting sides with plenty of ventilation. This provides grip for emerging adults, and you can add some sticks.  In summer conditions, you can incubate temperate pupae at room temperature, without further heating, but when it is cool you may wish to add warmth.  When you heat, the ambient temperature can be raised to 25º over a few days, and increase further to 30º if required.  The air around the cage needs to be heated: they don’t do so well if heat is directed at the pupae or the cage. Don't stand the cage on a heat source. You cannot over-water the cocoons as long as they are able to drain. You can hang cocoons: if you do they then need more frequent and heavy watering. 

The Pupae Nest is based on standard seed tray size 24 x 38 cms which fits the Standard Pyjama Cage. 

Exotic butterfly pupae should be incubated, totally shaded, in a tropical greenhouse. The ambience of a tropical greenhouse is not easy to emulate. Some breeders are successful in re-creating such conditions, but it us not sufficient simply to achieve a high temperature and humidity.  For details of how to attach tropical butterfly pupae to twigs, or bamboo, please see the introduction to the Exotic Butterfly section of the WWB website. Exotic butterfly pupae that are not suspended but lying loose, can be laid on the bobble foam of a Pupae Nest, and left uncovered. Remember incubating pupae must always be in full shade.


Size 5A  Plastic Box Shallow version of Size 5 174 x 115 x 41mm. Carton of 3.
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Size 5A  Shallow version of Size 5 174 x 115 x 41mm. Carton of 3.

This is the same dimensions as the popular Size 5 rearing container, but 41mm deep, instead of 60. This is advantageous for displaying mounted butterflies where the extra depth is a disadvantage. For storing pupae, particularly in the fridge, more boxes will fit a given vertical space, than the original Size 5 box.