Sadly I have had to remove my last post and rewrite it. This morning it was evident that things hadn’t gone to plan and in fact Treacle had died.
The good news is that wasn’t the real Treacle just one of his body doubles. The real treacle is absolutely fine but a bit confused about his size at the moment.
Unfortunately I am learning about this as I go along and there are some lessons to be learnt.
Collecting caterpillars from the wild means that they have been exposed to the perils of parasitoids. We have already seen one Tachanid Fly in action.
(Pelatachina tibialis)
In fact I am seeing these flies everywhere that I find Small Tortoiseshells, they seem to be very common but these are not even the main threat.
Major declines in Small Tortoiseshell numbers between 2003 and 2008 have been traced to another fly species Sturmia bella. One study of 5000 caterpillars taken from the wild found that 25% of them were killed by the larva of this one species.
Of Treacle’s doubles there have been a few casualties. I don’t have the resources to find out what killed them but I am pretty sure that it was parasitoid species.
I am sorry about the macabre photographs but this is learning.
It is just something to be aware of if you want to try raising caterpillars from the wild.
One way to avoid this would be to buy a kit. The animals supplied would not have been exposed to these risks.
Caterpillars are very fussy eaters and you generally have to have a good supply of their particular food plant, which is why I am raising Nettle eating animals. The kits available often contain Painted Lady caterpillars because they are one of the few caterpillars that can be fed with a food supplied with the kit and you don’t have to go out and get stung.
A painted Lady.
Whilst browsing WordPress sites I found one that I liked and found useful and I am guessing that he won’t mind me giving him a plug.
An enthusiast from Finland with more knowledge than me. His advice when collecting caterpillars from the wild was to choose small ones, the smaller the better as they have had less exposure to predators and are more likely to survive.
Pretty much the opposite to my original approach and I have taken that advice on board.
On a recent trip to collect leaves for food I managed to miss the fact that inside one of the tightly curled leaves were a whole bunch of little caterpillars and they are now running around in the Treacle-arium.
When collecting leaves I am normally careful to shake of any insects as I don’t want to bring anything else into the house but that is another issue. The fly that I mentioned earlier (Sturmia bella) gets her eggs inside the caterpillars by laying them on the food plant and hoping they will be eaten by a suitable host. To try and avoid introducing this parasitoid I pick nettles where there are no caterpillars present.
I don’t know why this caterpillar failed to complete it’s moult but there is a possibility that it was my fault.
I have been reading today that it is important to keep them out of direct sunlight as this can cause their skin to dry and harden and make a moult fail. We didn’t have direct sunlight yesterday it was an overcast day but I had put him in the best light that I had available.
I will never know but I will be a lot more careful when it comes to the real Treacle.
One other thing that I have learned: I have become very complacent about leaving my caterpillars uncovered because once they are settled on the leaves they stay there. It was not just coincidence that the last caterpillar was on the leg of my tripod.
They will stay on the food plant right up until they are ready to pupate and then they instinctively move as far away from it as they can before finding a safe place to pupate.
That presents a small problem for me and I am going to have to build a perimeter fence of good pupating sticks.
Well, I didn’t like writing this post and I don’t need anyone to “Like” it. It was just a hard lesson learnt. Crap really.
My enthusiasm is not dampened, I still intend to try and watch a caterpillar pupate into a beautiful butterfly and in the process I shall learn a lot more yet.
A Tramp in the Woods 