The caterpillars are growing fast – I have been feeding them leaves off my balcony plant and feeling guilty as the plant only has 6 leaves left and the caterpillars eat half a leaf a day and double in size. It is amazing how fast they are growing. In order to protect my plant I went on a walk yesterday and kept my eyes peeled for wild plants that I could raid for some extra fodder. Could not find a single one, with the exception of an absolutely beautiful 1.40m high specimen in my next door neighbours garden. I might have to go over and beg for some leaves. Thanks for all the comments on my caterpillars – Maria helped me identify them and thanks to her I now not only know what is eating my plants on the balcony but also that my plan is in fact not a foxglove or digitalis but is in fact mullein or Verbascum, also apparently known as a velvet plant. And my caterpillars are mullein moth caterpillars (Shargacucullia verbasci) – they are specialized on mullein, which is unfortunate as I only have 6 leaves left to offer, and the moths are a lot less attractive than the black swallowtail, although whether I find them attractive once again cannot be the deciding factor on whether they live or die.
So while they prefer Mullein I thought I’d try an alternative, I found a hairy plant outside my house the other day and thought may as well throw a leaf in and see if they will eat it and they are indeed eating it, albeit with less enthusiasm than they dedicated to the mullein leaf from my balcony.
Webresearch tells me that Mullein moth caterpillars eat Mullein, they are highly specialized, indeed they are so focused on this one and only plant that they are under discussion as a biological control agent to eradicate mullein plants where these have become invasive (http://www.nps.gov/plants/alien/fact/veth1.htm). And while they do apparently try to eat other stuff if they have no alternative, Mullein moth caterpillars fed other diets than mullein do not live significantly longer than caterpillars who were starved (http://www.nps.gov/plants/alien/fact/veth1.htm). So consequently I have a dilemma on my hands – I would like to keep my mullein plant alive, however I also want to keep the caterpillars alive, I will have to hand them over to Landkrauter in the event that an alternative home is on offer for the creatures, which I hope is the case, even if I am not offering beautiful Black Swallowtail butterflies……
Below to compare the black swallowtail caterpillar
And my Shargacucullia Verbasci – they are pretty similar I agree, but not close enough sadly.