Where have the caterpillars and moths all gone?

    
Don Herbison-Evans
( donherbisonevans@outlook.com)
&
Stella Crossley


Spitfire

Some years ago there seemed to be many Spitfires and Gum Moths around Sydney. Now there do not seem to be any. Where have they all gone?


Gum Moth

There have been several reasons suggested for this phenomenon.

  • One suggestion is that the replacement of the old incandescent street lights by fluorescents with their high UV output has disrupted the mating process of many lepidoptera species.
  • Another is that the build up of lead from leaded petrol exhaust deposited on the foliage poisoned them. If this is the case, perhaps they will come back soon now we are mainly using unleaded fuel.
  • Another is that the populations naturally go through random highs and lows. For example there was an amazing population explosion of Gardenia Bee Hawks in 2003 in Sydney, yet they were rare in the preceeding 10 years and also since in 2004.
  • It has also been suggested that the increasing population of Euro Wasps (Vespula germanica, VESPIDAE) is killing the caterpillars. These wasps have been observed cutting caterpillars up to take back to their nests.
  •  


    Gardenia Bee Hawk Caterpillar

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    (updated 24 May 2008)