Moths have a bad reputation because most people think that they eat clothes. In fact they do not. It is the larvae of a very few moth species that eat clothes. These larvae probably fed on the linings in birds’ nests before humans wore clothes made of natural fibers. Generally moths do not lay eggs on clothes made of man-made fibers or on laundered clothes, but, if you have an item at the back of the wardrobe that you haven’t worn for years, it might become infested with moth larvae about 3mm. long. Sometimes people think that their carpets have been eaten by moth larvae but it was probably varied carpet beetle larvae that were to blame.
There are 2,400 moth species in the U.K. but only about 60 butterfly species. There are two groups of moths: Micro and Macro. These are not based on size but on families. About 800 species are Macro, arranged in 56 families. Both moths and butterflies are Lepidoptera so they are closely related. Most moths are nocturnal (active at night) but some are diurnal (active in daytime) and some are both.
Ben explained that moths are considered to be scientifically important because:
- They are highly sensitive to very small environmental changes so they are a good indicator species.
- They are pollinators.
- They are at the bottom of the food chain and, as such, are a major source of food for birds and other animals.
The peppered moth is a good example of how changes in the environment can affect the species. It normally has white wings peppered with tiny black spots. In the past, when the atmosphere in Sheffield was full of industrial pollution and buildings and trees were covered in soot, an all-black form of the peppered moth was common. It was thought that the black form dominated because the white form was easily picked off by birds, but black form moths were camouflaged and survived to breed more black form moths, an example of evolution.
Moths have amazing camouflage. Many moths mimic dead leaves when they close their wings. Some look like bird droppings or sticks when their wings are closed. They are also good at pretending to be dangerous to predators. Some moths have large ‘eyes’ on their wings which make them look dangerous. Some have coloured bodies that make them look like hornets. One large moth flutters its wings rapidly so that it looks like a humming bird. Another has a yellow head and upper body and a ‘beak’ so it looks like a canary.
People think that moths are brown and have furry bodies, but many species are beautifully bright coloured with very complex patterns on their wings. Many moths are just like butterflies to look at. The green carpet moth’s wings are emerald green with a pattern like a carpet. It feeds on bilberries on the moors around Sheffield.
Some moths have caterpillars that look like sticks or pieces of wood. The elephant hawk moth’s caterpillar is about 10 cm. long (and looks like an elephant’s trunk) but is coloured with patterns and ‘eyes’ so it looks like a small snake. The sycamore moth’s caterpillar is about 5 cm. long and has bright yellow hairs sticking out all round. This seems to put off predators. Some caterpillars are tiny – the horse chestnut leaf miner burrows between two surfaces of a leaf, eating away in safety until it is large enough to pupate. Another caterpillar, only 2 mm. long, rolls up a leaf into a tube and eats away inside it.
Ben showed a photo of his moth trap (a bright light over a funneled box) which he used to catch moths in an area of well-mowed lawns near a University Hall of Residence. He caught many moths but they were all of one type. He said that this was because the available food suited only this moth type. He suggested to the Hall residents that they let the grass grow and allow other plants like buttercups, daisies and plantains to grow in the grass. When he set up his trap sometime later he caught several different types of moths. He said that if we want a wide variety of insects (he meant moths!) in our gardens then we need a wide variety of plants and not to spray chemicals at all.
At the end Ben was asked what is the difference between moths and butterflies. He admitted that, in fact, there is no real difference. This was a fascinating talk with so much new information that I’ve only scraped the surface.