Basin Notes

by Andy Wakelin

HANDS up – who likes moths? Fie on you, if you did not raise your arm even a little. How about butterflies? Ahh! Nearly everyone has a limb aloft.

To the man in the street distinguishing butterflies and moths is usually done on the fact that butterflies are big, brightly coloured and fly during the day, while moths are smaller, generally drab and fly at night. Hence butterflies are much more widely appreciated.

In technical terms, both moths and butterflies are in the family ‘Lepidoptera’. The species of moths are roughly split into macro-moths, which are the larger, more butterfly-like moths and micro-moths are all the small moths. This simple nomenclature allows lepidopterists to broadly classify what they see and is a useful way of starting to identify them more precisely. In the UK there are about 70 species of butterfly, about 900 species of macro-moth and about 1,500 species of micro-moths.

There are exceptions to this way of grouping these flying marvels. Some of the larger and more colourful moths (for instance six-spot burnet and hummingbird hawkmoth) like to fly through the day and can be seen in gardens around the country if you have their preferred plants.

To add further confusion to our simple scheme, some recent research has shown that butterflies are more closely related to pyralid and crambid micro-moths than the larger macro-moths.

So while we all love butterflies in their adult form, gardeners dislike the larval form as the caterpillars can devour their carefully nurtured vegetables and flowers. Chief amongst them is the caterpillar of the large white butterfly which will decimate your cabbage patch in no time. So anyone cultivating their ground for profit or pleasure will say: “Why me?”.

Well, a lot of butterflies and moths will lay their eggs on specific plants because the larvae (caterpillars) need to feed on that plant and only that plant. The problem that lepidoptera have is that in all stages of their life cycle they are preyed upon by many creatures eager for a tasty package of protein to sustain their own bodies or those of their offspring. For example, a blue tit may need as many as 15,000 moth caterpillars to raise a single brood!

This means that a female moth or caterpillar must lay lots of eggs, knowing that at every stage the number will be reduced by disease, parasites and predators until only a few will survive to adulthood and be able to breed. Typically this is 100-200 eggs which are spread over an area with suitable food plants, so that there are not too many on the same plant which would put the larvae at risk of starvation once the plant had been eaten up.

So if you have a large cabbage patch, the large white will lay eggs on all the plants to give her offspring the best chance of getting all the food they need. However, seeing all your carefully cultivated cabbages full of holes can be soul destroying.

However, if it wasn’t for all those moths and butterflies in all the stages of their lives, there would be a gap in the food web and the predators (birds, small mammals, spiders, beetles, earwigs etc.) would struggle to survive and our gardens and countryside would be a poorer place.

So, raise your hands if you like moths and butterflies – that’s better.