Beware of what’s hiding in the undergrowth: they’re black, very hairy and large – well, by caterpillar standards anyway. Woolly bear is the nick-name given to the caterpillar of the garden tiger moth because, as the name suggests, it’s covered with hairs – lots of them. It looks black but in reality the hairs are a mixture of colours: shorter black ones and ginger ones nestling amongst long white-coloured ones.
These hairs are a pretty effective means of protection – they contain a chemical that causes irritation to anything that touches them. This, though, doesn’t seem to bother the cuckoo one bit which can eat it as part of its balanced diet.
However, predators don’t know what they’ve let themselves in for if they eye up the caterpillar when it’s grown up: the caterpillar turns into the garden tiger moth which has a black belt in self-defence with not one, but three ways, to fight back.
Round one: a flash of its brightly coloured orange -with-blue-spots hindwings. Normally, when sitting on a plant, the wings are folded over the moth’s back so only the black-and-cream upper wings can be seen. If a predator gets too close, the moth quickly spreads out its wings to create a sudden splash of orange. In the natural world, red and orange colours signal poison or danger and are a message to keep away.
Round 2: If the hint isn’t taken, next tactic is a high pitched grating noise made by rubbing the wings together rapidly. Bats are particularly susceptible to this tactic given their hearing is tuned into high pitched noises, and they probably link the sound with a distasteful meal. A handy tactic when you remember that this moth flies at night along with bats.
Round 3: if the predator is really determined (and hungry), then the moth’s final trick is a distasteful yellow fluid squirted from just below its head. And if all that doesn’t work – well, the predator then deserves its meal for sheer tenacity.
The adult moths look spectacular with cream and brown-coloured upper wings which have patterns similar to a giraffe’s, the brilliantly coloured orange hindwings, and its abdomen (‘stomach’) which is orange with black stripes – who says moths are all brown and boring?!
The caterpillars are around in May and September feeding on a variety of different plants like nettles, dock, burdock, lettuces and many garden plants. Those hatching in May finish growing by end of June and turn into a chrysalis, emerging as these stunning adults in July and August. Fascinatingly, these are one of the few tiger moths which don’t have a tongue – so all that time developing into a grown-up and then they can’t even have a tasty meal. Seems a rough deal.
The fifty or so eggs laid by the female garden tiger moth hatch August to September but after feeding themselves up, these caterpillars over-winter and appear again in spring ready to start the cycle all over again.
Unfortunately, garden tiger moth numbers seem to have crashed by up to 98% in the past 50 years. ETD (Ecological Tidyness Disorder leading to neat gardens, parks and open spaces, and the liberal use of pesticides and herbicides) is one of the reasons, and climate change is another. This moth needs cooler climates like ours, and certainly wouldn’t be donning its sunglasses to head to the warmer ones of southern Europe. But climate change is leading to more January’s being milder and wetter, followed by sudden temperature drops in February. This combination seems to be causing lots of caterpillars to die and, therefore, fewer adult moths around in spring and summer.
So, embrace ‘untidiness’ in your garden! And help not just the garden tiger moths but lots of other wildlife, too.
A Year of discovering Stroud's wildlife 