Wednesday, January 23, 2013

The red leaf beetle

Red leaf beetle (Chrysolina gossa)
The red leaf beetle is one of about sixty species of leaf beetles that are found in the Maltese countryside. The leaf beetle family is one of the largest and most commonly encountered of all beetle families with over 35,000 species in the world.

They are all plant eaters feeding on specific plants and several species have been used to control weeds. This was particularly successful in parts of Australia and in California where introduced plants were causing a lot of damage because of lack of herbivorous animals that could control them.

In Maltese the red leaf beetle is known as żabbella ħamra. Żabbella is a variation of the word sebbella which is one of the several, mostly forgotten Maltese name for the ladybird which is more commonly called nannakola.

 Beetles are the largest group of insects. It is estimated that there are between five and eight million species in this group this being about 25% of all known life-forms. 40% of all described insect species are beetles and many new species are discovered every year.

Beetles and their larvae have a variety of strategies to avoid being attacked by predators. These include camouflage, mimicry, toxicity, and active defense.

Camouflage involves the use of colouration or shape to blend into the surrounding environment. This sort of protective coloration is common and widespread among beetle families, especially those that feed on wood or vegetation, such as many of the leaf beetles. In some of these species, sculpturing or various coloured scales or hairs cause the beetle to resemble bird dung or other inedible objects.

Another defence that often uses colour or shape to deceive potential enemies is mimicry. A number of beetles resemble wasps which helps them avoid predation even though the beetles are in fact harmless. Many beetle species, including ladybirds can secrete distasteful or toxic substances to make them unpalatable or even poisonous. These species often have bright or contrasting colour patterns to warn away potential predators. There are many beetles which mimic these chemically-protected species including the red leaf beetle which resembles a ladybird.

This article was published in The Times on 22 April 2009.

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