Bird's Eye View of Bute

Thistle Tortoise Larvae

(1) First Stage
(1) First Stage
(2) Preparing to cast off
(2) Preparing to cast off
(3) Predator about
(3) Predator about
(4) Casting off
(4) Casting off
(5) Second Stage
(5) Second Stage
(6) Changing
(6) Changing
(7) Changing Again
(7) Changing Again
(8) Final Stage
(8) Final Stage

 

 

 

Island Life

Well! As I said recently, that I had a great year of finding new things on Bute, and now this it is time for you to see one of them. This is what I call a nasty -wee creepie-crawly that is only 7millimeters, ( about a quarter of an inch) in length, but it is one horrible looking thing, and I was not sure if it would jump, fly spit or whatever at me, so I treated it with care.

 


During July last year,(2009) up between the Dhu Loch water works, and Achamore woods, I was looking for caterpillars of the Marsh Fritillary species, as one colony had before been found at the North end of the Island, and again at the South end, and I had found a third site over Scoulag moor, so I was now looking for a fourth site.
I was finding plenty of other species, like the caterpillar of the Painted Ladies, as there had been a very large influx of the Painted Ladies arriving in the UK.
Then I found what I thought was the one's that I was looking for, but,no, it was Peacock caterpillars, and plenty of them,. then on a thistle, ( not the one that we know as the “Scottish Thistle”, but the “creeping thistle, which is similar in height but has smaller leaves and flowers ), was this ugly wee thingy, (1) First Stage so being me, out with my camera , and take images of it.
I sent the image to Glyn, ( the Moth Man) who checked the records for it but found nothing, so he sent it to Jeanne Robinson, who gave a talk in the Museum for the Buteshire Natural History Society, and is in charge of all the Museums in Glasgow, and is one very clever lady, and she sent back that it is a “Thistle Tortoise Larvae”, and as you can see it looks nothing like a tortoise, but read on.

As no records of it were found, I decided to check, and record , the whole island for it, with good results.
It is back breaking work bending down all the time, so next time I will take a small folding seat. As it takes a while to cover all of Bute, I was able to see how the wee nasty evolved. It only eats the top of the leaf, and as it eats and then defecates it catches it with its twin appendages at its backside , and folds it over, mixes it with its skin castings, and covers its whole body with it to protect it from ants, and it is called frass,(poo). or excreta. There are umpteen hundreds of these thistles here, and sometimes, after checking about fifty with nothing on them , I would find one with five on it. As the weeks passed the thistles showed the results that these wee beasties had on them. as the leaves all the way up were in a bad way, they had been the main diet for them. This made it easier for me ,as I did not have to bend down, I could see from a standing position if the plant was occupied, making my life a lot easier.
Then , prior to pupation (change) the accumulated waste on their back was discarded.then they start their metamorphosis, and the top of them now went very dark as it was exposed to the air, (5) Second Stage , and it was still only 7mm. As you can now see yourselves the mess it made of the plant.

All in all I found 56 plants on Bute that had at least one on it, and some with as much as five, so I had good results, then they were changing again, and this time , they were very hard to find, as all the legs that were sticking out from the sides had been drawn in, and they had turned green, (8 ) Final Stage the same colour as the plant, and you could be looking at them but still not see them, ( OK, looking at something but still not seeing it is stupid, but you get my meaning), its camouflage is so good that they will only be seen from a side view
When they were at Ist and 2nd stage they held on tightly to the plants with their legs, but at the 3rd stage, if you touched the plant, they would fall off on to the green grass, making the impossible to find. I was very lucky, as I touched one plant ,one of them fell onto my upturned hand. Fortunately it was my left hand, so I was able to get my camera out and take a photo of it, then I put it on top of a corner post of a fence, to get a better shot, and the wind blew it away, and I never saw it again,or another one.

Although I covered the whole Island, finding many of the plants, lots of areas had no Thistle Tortoise Larvae on them , so this year I will covers all areas that had plants but none on them .

Norrie Mulholland

First Published in the Buteman 05-03-2010.


Well I did search for them in the areas that I had found none last year, but I found very little of them at all anywhere, so I was very lucky that I had done a survey for them on 2009.


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