Wednesday, January 2, 2013

A moth that ‘measures earth’

Small dusty wave (Idaea seriata)

The small dusty wave is a very common moth. It does not have bright colours, unusual patterns or features and is easily overlooked.
From that perspective, I could observe the way some moths hold themselves tightly to a wall and the way they hide their antennae beneath their body to avoid detection by predators.I recently found a small dusty wave resting on a window pane, which gave me the opportunity to look at it closely and to photograph it from underneath. Looking at plants and animals from unusual angles adds interest to even the most mundane species.
The small dusty wave is found throughout most of Europe, the Near East and North Africa. In Malta it can be found from May to December. In colder countries it appears as late as June and disappears as early as September. Like most moths it flies at night and is often attracted to lights.
In Maltese, the dusty wave is called idja komuni – a name coined by lepidopterists from its scientific name Idaea seriata.
The caterpillar of this species feeds on various plants including ivy and has a preference for dry leaves.
The small dusty wave is a geometer moth, a name given to members of the Geometrid family. This is a very large family with about 35,000 species worldwide.
The name comes from two Greek words: geo meaning earth and metron which means to measure. This name was given to them because their caterpillars move in a looping fashion, a movement we must have all seen at some time or another in a Disney cartoon.
When moving, these caterpillars hold on to the ground with their front legs and then pull their body forward. They then hold the ground with their hind legs and push their body forward. In this way they give the impression that they are measuring the earth.

This article was published in The Times on 2.2.13.

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