Sunday, May 20, 2012

Beetle mania

Recently while taking some early morning pictures at Fiddien I found a species of black beetle that I had never seen before. A friend of mine, a specialist in beetles, identified it for me.

It was a nocturnal weevil known to entomologists as Otiorhynchus lugens but for which I could not find a common name.

Weevils are recognised by their long snout and small antennae which have small knobs at the end. They are plant feeders and are often found on or near their food plant.

The weevil family is very large. Over 40,000 species have been identified worldwide of which more than 120 species, including several endemics, are found in the Maltese islands.Most of the weevils I am familiar with are either a shade of brown or grey.

Being black and nocturnal this species made me think about the fact that although the most familiar beetles such as ladybirds and leaf beetles are brightly coloured, many beetles, many of which we do not often see, are black.

A study carried out about ten years ago in Brazil found that the body colour of beetles is strongly related to their daily activity pattern. In other words, nocturnal beetles are likely to be black while diurnal species are either brown or brightly coloured.

Bright colours are used to warn predators, especially birds, that that particular insect is either bad tasting, poisonous or that it can inflict a painful sting. Brown or grey colours camouflage them, making them difficult to see against their surroundings. On the other any brown or grey beetle would be easy to spot in the darkness so nocturnal beetles have evolved black bodies which makes them difficult to see at night.

This gives them an advantage over beetles that are not black, as, being more difficult to see there is a smaller chance that they are eaten by predators.

This article was published in The Times on 28.12.11

No comments:

Post a Comment