Caterpillars

Around August we receive one request every second day for information about a very peculiar and extremely large caterpillar found crawling across paths and patios.

So used have we become to this that I can virtually describe the caterpillar before the caller commences. They are about five centimetres long, a chocolate-brown colour with some lighter patches, smooth coated and the thickness of a small cigar.

After feeding for weeks on fuschia or rose bay willow herb, the fully-grown caterpillar is now searching for somewhere to pupate - usually beneath moss or dry leaves on the ground, out of the reach of frost.

There it will remain in a chrysalis until the end of the following May when a beautiful pinkish Hawk Moth will emerge to start the cycle all over again.

The warm, dry summer in Scotland in 2000 played a part in confusing people into thinking they have seen something unusual in this country. We have received several phone calls from folk convinced that they have a hummingbird in their garden. What they have really seen is the bluish-black hummingbird hawk moth.

In flight, this moth looks just like a hummingbird in flight, with its wings a total blur.

It is very common on the continent and in parts of southern England where it is warmer and dryer, and the prolonged spell of fine weather we have been enjoyed has attracted many further north.

I watched a hummingbird hawk moth hovering on front of a display of geraniums and I was struck by how the grey and black markings of its abdomen bore a striking resemblance to the olive-black shield-like head of the grass snake.

I am now convinced this protects the moth from birds such as flycatchers, which must be strongly deterred by the threat of being grabbed by a snake.