Breeding butterflies to free them in the wild

Hello Mario,
the result of zero might be right.
I tried to breed some 50 caterpillars of Antheraea occulea on an oak in my garden and I controlled them every day.
After growing easily, I had to watch wasps suddenly in the 3rd instar started to hunt the caterpillars intensively. In only one(!) day, they found all of them and killed them all! Not only one caterpillar survived! What a massacre.
This shows, that it should be very hard to establish a species in nature.
To have a stable population, there should only survive 2 individuals from one breeding pair! If there will be more survivals, the number of individuals of a population will rise and explode after some generations.
Thats the reason, why some species lay such a big number of eggs (and S.cynthia do so). They were hardly hunted by predators! A stable population of S.cynthia needs some douzen maybe hundered individuals to lay some thousend eggs. Lets calculate 100 female S.cynthia in an area, each one laying 200 eggs. So if all of the eggs hatch, you have 20.000 caterpillars in L1! There will, at the end of the year, survive only 400 individuals (200 male and 200 female)!!!
15 cocoons means perhaps 8 female and 7 male. This is not a successfull number of cocoons. The number of 1600 eggs might be not enough to create a new generation.
So if you want to establish them, you perhaps have to set free a big number of caterpillars (some hundereds!)or some more cocoons, but not on the same plant and the same place. You should spread them over a big area, single on divers plants, so that predators do not find them easily. The more they are spread on different plants the possibility is higher, that they survive. And you should imagine that caterpillars of this size and the cocoons have a lot of predators! Birds, insekts, mice, parasites,...all are searching for them and big caterpillars are realy easy to find.
The searching of cocoons is perhaps not the best method to control the population. The caterpillars wander bevor hiding the cocoons very good and if you do not know, where to look for them, you will not find one of them! Better you look for the adults, they are easily to find on lighttraps in spring.
Arnd

Hi I had wasps discover newley hatched sinensis larvae in the greenhouse and take over 100 in less than 2 hours, as you have a good number of cocoons I would breed them in captivity then glue 50 or so eggs to twigs and tie in the trees when they come into leaf.this would put large numbers to start I have always used Pritt stick glue to glue silkworm eggs in trays with no ill effect,good hatch rates on the eggs.Good luck

Hi Mario,

I wouldn't recommend releasing foreign butterflies in your area. There are many cases of species that became terrible pests after humans introduced them in new areas. Moreover, many introduced species have also displaced native species. It is also possible that the specimens you obtained from abroad, carry diseases (bacteria, viruses) that may have a negative impact on the native lepidoptera. Releasing livestock may give you a good feelding, but you certainly aren't helping the local ecosystems. Even lepidoptera are not harmless!

Regards,
Klaas

I totaly agree with Mario. Samia cynthia has never been a problem as I know. It is widely spread at the Garda Lake and perhaps the south of France regions and he never appeared as a pest. And the argument of spreading bacteria or virus.....we can´t imagine, what modern trafic does to all oekological systems. Train, car and ship traffic is the problem, the carrying of goods all over the world in shortest times. So is one of the problems the spreading of mushrooms or bacteria by train. Along the embankment the feeding of cattle is a big risk, because you have a transportation of germs all allog their ways.
So what are we talking about?
And Mario, I do not think that you have been the reason why S.cynthia disappeared. Perhaps there have been some bad years for the population too and the number of individuals have been to small for a long lasting successfull establishment.
Arnd

Zitat von mario_lorenzi

Hello!
I am currently buying and breeding butterflies with the objective of freeing them into the wild.
I am now trying with Samia Cynthia,

Hi Mario and Arnd,

Of course Samia cynthia as a species won't cause much harm to the environment in southern Europe. I was referring to the quote above, which does not mention 'freeing' only Samia cynthia, but butterflies in general.

I wouldn't be surprised if the pathogens that cause diseases in butterflies and larvae in far away places are different from the ones our native lepidoptera are adapted to. Why risk introducing them to the environment in your area? Some pathogens like Wolbachia infect certain lepidoptera species and live intracellularly. This means they need the butterfly to infect other butterflies. In the past decade Hypolimnas bolina became almost extinct on 2 Samoan islands, after the species became infected with Wolbachia. The microbe kills all male embryos, so after some years less than 1% of the aduts were male.

Regards, Klaas