Attempting to Breed Nymphalis antiopa

We are now attempting to breed our mourning cloaks (Nymphalis antiopa). They originated from an egg cluster collected on willow (Salix) along the Ohlone Greenway Trail (Berkeley, California), June 29, 2017.

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Many more dozens of antiopas swarmed our tub again today, and this time there are a lot more of them are female. Most of the males have all eclosed, and maybe a few dozen more females are still left to eclose. The tub is soaked in their bright red meconium. We took a few more out to photograph as well.

We have not released any of the butterflies that have eclosed so far and have been keeping them all in the tub. Since a good majority of them are already eclosed, we decided to give breeding them a shot. We have no experience breeding these before or any similar nymphalids, but it is possible and has been done before by some. The general idea is to just get them all in a large screen cage around the host and food sources in full sun and wait patiently, and hopefully they mate naturally and lay eggs.

For our set-up, we have a large self-constructed wooden screen cage around a small potted willow tree we propagated back in the spring as the host and a live milkweed plant rooted to the ground as a nectar source. Whether or not the butterflies will actually drink from the milkweed flowers, we do not know yet, but so far they don't seem interested. In the wild, antiopas seldom visit nectar flowers and instead prefer tree sap and rotten fruit. If it turns out that they will suck from the milkweed in captivity, then obviously it is the simplest way to provide a food source. However, it may not be the case, so we will most likely need to provide them with some of their preferred food. Others have used bananas and sugar water which would be quite simple to provide them with.  

We have put several dozens of the butterflies into the cage and could have put more, but overcrowding will likely make it harder for them to mate. So far, they don't do much at all, just resting wings closed along the sides of the cage just like they do in the tub. Or, when the sun is over them, some will open their wings and bask. Only when disturbed do they flap around for a bit before returning to resting. 

If after several weeks they do not mate or lay, then perhaps it is because they are hibernating, as the overwintering stage is the adult. In that case, they will pull over until probably next March or April and perhaps then they will breed. In our area, we usually stop seeing antiopas flying past July, and they only seldom have another brood at this time. However, our butterflies were reared indoors as larvae and received a much longer photoperiod than in the wild, so possibly that might've tricked them into not going into hibernation as adults. This is our first time rearing this species so we simply do not know. We'll just wait and see what happens.

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Authors
Alan Liang

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