Abseiling on silk

I returned to Seychelles in late April 2016 to mixed weather: some sunshine, some cloudy days, some light showers, some heavy showers, some hot days (usually very humid), some cooler days, and variable winds in terms of strength and direction. These conditions are fairly typical of the changeover season following the wetter north-west monsoon in November to February-March and before the onset of the drier trade wind season, from May to October, with its steadier and sometimes strong south-east winds. These changeover conditions did however provide me with goo acclimatisation conditions, especially almost mirror calm seas with warm and clear water for bathing!

One event that I had witnessed during my visit in December-January had remained

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Senir plim caterpillars descending on strands of silk

constant, however. This was the descent on silk strands of hairy, black and orange banded, caterpillars (locally called senir plim, see blog post of ?? December 2015), from their feeding grounds on the leaves of suitable trees, some very tall such as mango trees. Their presence was betrayed by the silk strands shimmering in the early morning sunlight when caught by a light breeze.

These caterpillars can cause problems wherever they occur in environments close to people because their hairs, which can fall off the caterpillars and be carried by the wind, can cause severe irritation and skin rashes in those unfortunate enough to come into contact with them. Those working in gardens and woodland are particularly susceptible, but unwitting tourists have also occasionally been affected by them. This can happen as the caterpillars hang un-noticed from the trees on their silk abseiling journeys. It appears that this invasive species is now well-established in Seychelles despite the array of chemical sprays and fogs that have been employed against them.

This is only one of many examples of invasive species that have entered the island nation by uncertain routes and causing problems to residents and visitors alike, and sometimes also affecting the islands’ wildlife. Once established, management of invasive species can be difficult, prolonged and expensive, highlighting the importance of efficient biosecurity at all possible entry points. The rapid spread of the moth to many of the islands in the Seychelles archipelago illustrates the danger of failure to eradicate invasive pests as soon as problems are identified.

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