General considerations on adult Lepidoptera
Lepidoptera adult stage, which is the final outcome of metamorphosis, consists in the butterfly or the moth. The adult stage is also called imago. This stage has lost the capability to increase in size, task which is completely committed to the larval stages. Even if many adult Lepidoptera feed as adults, this is not reflecting in their overall size, which is determined by the final size of the mature larvae.
Thus, the function of Lepidoptera larval stages (caterpillars) is to feed and increase in size, while the main tasks of the adults are to disperse and to mate quickly, in order to produce a numerous offspring. This is the reason why adults have wings. Wings help in covering long distances to find a partner and allow seeking for the proper place where the next generation will grow.
As in all the other stages in the Lepidoptera life-cycle, there is a plethora of variability in behavior and needs. The main difference that we can encounter consists in the flight time. The so called butterflies use to fly, and pair, during the day while moths do it in the night time. As always, there are some outsiders as Saturnia pavoniella, which is a moth (Saturniidae family), but flies during the day.
Another main difference is the ability and the propensity to feed. There are different cases:
-Adults that do not feed at all (all Saturniidae, some Sphingidae and others)
-Adults that may feed but is not necessary in captivity (ex. Sphinx ligustri, which is able to mate and lay eggs without feeding, although feeding increase the lifespan and the number of eggs laid)
-Adults that need to feed in order to pair and lay (many diurnal butterflies and most Sphingidae)
Between the feeding ones we can also distinguish in:
-Adults that feed by themselves in captivity
-Adults that need to be hand fed
So… being reproduction the purpose of the adult stage of Lepidoptera, the breeder wants to maximize the chances to get a pairing and thus fertilized eggs to start a new cycle.
Here we need to distinguish between 3 main groups of lepidoptera that we deal with: diurnal butterflies, Saturniidae and Sphingidae.
Saturniidae/Sphingidae: moths pairing
Antheraea jana, male and female during copula
Saturniidae moths have lost the ability to feed as adults during the course of evolution. Their mouth parts are not functional thus their lifespan is generally short (5-8 days depending on temperature). They can only rely on the energy stored by the caterpillar during the course of its larval stages.
They have no time to lose after emergence, female can pair from the first night out, males can also do so but they are generally more active the second and the third night after emergence. Saturniidae and Sphingidae are moths so they mostly pair during the night.
To arrange a good setup to allow them to pair spontaneously you just need to find a good cage/habitat (our 40x60cm rearing cages are good for almost all the species you may find). The place where you should leave the cage overnight is the most crucial part. To increase the chance of a pairing, you can leave the cage by an open window, which will provide the right airflow, or even leave it outside if temperatures are not very low (around 15°C is best, but species like Actias luna or Hyalophora cecropia will pair even if temperatures are around 4°C. Make sure you find a place inside your house where nobody is going to turn on and off the lights during the night (this is going to disturb them). Better to avoid 100% dark rooms, moths use to enjoy smooth night-light. If you think, in nature, is not common to have a completely dark night. If the room is ventilated this can increase the chances of pairing. For Sphingidae species, it’s recommended to add some branches of the preferred host-plant in order to stimulate pairing and egg laying.
If you proceeded this way, and you were lucky enough (unfortunately there is always a random component), you should find the adults together the morning after. Most species remain attached (by the posterior tip of the abdomen, where there are genitalia) until the following night. Do not try to divide or move them until they are together. For some species, as many Actias sp., the copula can last few hours. If this happens, you may not find the adults together the morning after.
Once the adults have separated from each other, remove the male from the cage because it may pair again with the female the following night, impairing egg laying. One copula is sufficient to provide enough sperm to fertilize all the eggs that the female will lay.
Egg laying: Saturniidae females do not need any special care to lay eggs, just leave them in a rearing cage with day/night light cycle and they will lay many eggs on the cage’s mesh over their short lifespan, on the contrary some Sphingidae will only lay on their larval host plant. Include some cutted branches inside the cage or a small potted plant. A single female can lay from 50 to 500 eggs depending on the species and the size of the specimen
Diurnal Lepidoptera: butterflies pairing
Melitaea dydima, male and female during copula
Diurnal butterflies, like Pieridae or Nymphalidae, need sunlight and warmth in order to pair. Given that, many species will readily pair in our 40×60 mesh cages, large enough to to home some flowers and the proper host plant. They usually pair early in the morning when the hot sun strikes them, making them active. They will look for the food and a the right partner. Some species (EX:) will need direct sunlight while others (EX:) will pair and lay even in the shadow. Make sure to start feeding your adults the day after emergence, once or twice a day depending on the weather. If it’s not that hot where you’re keeping the adults, once may be enough. If they’re exposed to direct sunlight most of the day, you’ll have to feed them twice and also make sure they can feed by themselves, both on cut flowers or on honey-water 1:10 solution.
Most species will pair for just 30 minutes to 1 hour, making it difficult to know which females are paired and which are not. Luckily, with diurnal butterflies, we know most of them lay eggs only if fertilized and many eggs of various species will change color the day after being laid, making it easier for us to spot fertile eggs. Please note that most species will need their larval host plant in order to lay eggs on it. As always, there are some exceptions as the members of Nymphalidae family, which can lay many eggs in a paper bag with just one or two larval host plant leaves.
As for pairing, sun and warmth is crucial for egg laying too, which usually takes place the day after mating. Many species ‘taste’ the host plant before laying eggs, by their antennae or by their legs. Since these are very vulnerable parts, it may happen to break them while handling the adult. A female with 1-2 missing legs could not lay a single egg because of this, so always be careful and gentle, grabbing the adults by their wings where they’re more resistant. This detail is very important and should be kept in mind, especially when adults are handled for rehoming, feeding or hand-pairing:
Hand-pairing: how to force copula
Female Attacus atlas hand-paired with a male A. lorquinii
The so called “hand-pairing” technique is the last choice when adults do not pair spontaneously. It consists in forcing the copula by manually stimulating both the male and the female to pair. Such technique is not useful with all species, some may be reluctant to be handled. Saturniidae and some diurnal butterflies are more prone to be handled and forced to pair..
When to handpair: Choosing the right moment to handpair Lepidoptera is key in order to achieve it successfully. For nocturnal Lepidoptera, the best moment is during the night, after the female starts calling and the male becomes active, looking for the female to pair with. The female is ready to promptly pair after emergence. The male does its best in the second and third night after emergence (Saturniidae). For diurnal it is better to perform the hand-pairing during the day, and make sure the males are well fed and 2-4 days old. Also, it’s best to wait some days before trying to hand-pair diurnal butterflies because in this period genitalia will harden and you’ll lower the risk of damaging them while trying to do the handpair. Many diurnal butterflies’ males need minerals to mature sexually, so we feed them with a honey-water solution with a drop of soy sauce, it works very well.
How to handpair: Gently grab the female with one hand and the male with the other, using 2 or 3 fingers. Be careful of holding them by the thorax, maintaining the wings closed dorsally. The goal is to stimulate the male to open the claspers (located in the posterior tip of the abdomen), which are used to hang the female and build a stable contact with it. Create contact between the bodies of the two specimens by rubbing their abdomens. Then start to rub the tip of the male abdomen up and down against the female’s posterior tip of the abdomen (where the genitals also are). It is possible to use different movements, quick up and down, slow up and down, rotations. The operator will need to practise for a while before gaining confidence with this practise. If the male doesn’t want to open the claspers, gently press the abdomen in order to stimulate it. The same can be done to the female, to force it to extrude the genitals. Be aware that males needs to grab the female in the correct position, slightly over the ovipositor.
If the procedure is done correctly, male should open the claspers. When it does so, keep on rubbing them, but slowly. This way the male gran grab the female autonomously and proper stick to it.