Small Tortoiseshell Butterfly, Aglais Urticae



The small tortoiseshell butterfly used to be one of the most common British butterflies but sadly it’s been in steep decline in recent years. Therefore it was very cheering to see a number of them fluttering around the allotment this week and they seem to love basking on the chives.

The small tortoiseshell butterfly is one of the first butterflies seen in the spring. It has an interesting life cycle, like brassica’s and leeks it over-winters! Okay, hibernates. There are two generations of small tortoiseshell each year, and it’s the second generation that hibernates. The butterflies find a sheltered spot during the coldest harshest winter months to hibernate and then emerge as the days start to warm up in March and April.

In the spring the female lays around 70 to 100 eggs on young tender common nettles, the caterpillars main eating habitat. After about 10 days the caterpillars appear, they spin a dense web over the plants growing tips for protection. The caterpillars tend to stay together as a group when young, only dispersing if there is insufficient nettles to eat and then to pupate. The caterpillars eat non stop for about a month; I’m thinking back to that wonderful children’s book, The Very Hungry Caterpillar by Eric Carle, although I’m sure these caterpillars don’t devour cupcakes or Swiss cheese! Once nice and plump they are ready to pupate. They can travel, waddling obviously, up to 15 meters to find a suitable safe place to pupate. The adult butterfly emerges after about a month. The first of these butterflies appear in July.

In conservation terms it’s worth cutting down nettles in June, it makes great compost. New tender shoots appear in July/August just as the small tortoiseshell is looking to lay eggs. The breeding cycle starts all over again. The first of these butterflies appear in October. The average lifespan of a small tortoiseshell butterfly is 8 months.

The small tortoiseshell butterfly is a welcome addition to the allotment as it helps pollinate our crops without devouring them like the super pest of last year, the cabbage white butterfly. There were so many cabbage white butterflies last year, at one point the blue sky looked full of white confetti. I’ve seen quite a few cabbage whites already this year but we are much better prepared to tackle their greedy brassica loving caterpillars.

Just as aside, whilst staying in Carriacou, a beautiful tiny island in the West Indies, earlier this year I saw this catapillar.



It’s a Frangipani caterpillar, a magnificent creature, measuring about 14cm long. And it makes me rather grateful the cabbage white caterpillars don’t grow to this size.

Posted in Insects

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May 2014
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