Thursday, 19 March 2015

Three Arthropodean Visitors

..... a moth, a beetle, and a spider.

While I have not been actively searching for interesting spiders and insects, I have crossed paths with several over the last week or so..

1. Southern Old Lady Moth

Southern Old Lady Moth, Dasypodia selenophora - Close up showing labial palps and coiled proboscis

Southern Old Lady Moth, Dasypodia selenophora - Dorsal view

Southern Old Lady Moth, Dasypodia selenophora -  Detail of wing scales

 (click to enlarge)

The Southern Old Lady Moth, Dasypodia selenophora, can be found in the southern half of Australia, as well as Norfolk Island, New Zealand and Macquarie Island. One particular Southern Old Lady Moth can currently be found in my house. They like to hide in dark places by day and so they often come into houses or other buildings.  After taking the above photos, I wanted to coax it onto some glass so I could photograph the underside. However, the sprightly old lady made it's escape and has not been seen since.

Why is it called "Old Lady"?  Probably for the same reason as another moth of the same name in Britain. The pattern was said to be like that on an old lady's shawl. Another common name for this species, Golden Cloak Moth, suggests a similar meaning.

So how do the moths get down to Macquarie Island (1546 kilometres south of Hobart). Apparently they hitch a ride on prefrontal airflows (northerly winds) ahead of cold fronts.  In one such event it was estimated that the Old Ladies, flying at 300m asl, could have reached Macquarie Island in under 10 hours. A nocturnal temperature inversion kept the temperature at above 5C.  They would have been traveling at around 100 m.p.h. What a ride!

2. Fuller's Rose Weevil

Fuller's Rose Weevil - Asynonychus cervinus - Lateral View (Click to enlarge)

This 8mm long, beetle was found in the garden on the underside of our rhubarb leaves. Some one on the Bowerbird web site has identified it as Fuller's Rose Weevil (Asynonychus cervinus). It is an introduced pest in Australia and many other countries, probably originating from Central and South America.   It has a large number of host plants but is best known as a pest of citrus. So, you may wonder,  why is it named Rose Weevil? According to the University of Florida Entomology and Nematology Department, this weevil "caused considerable damage to winter roses when it was first reported in the United States from California in 1879."

The elytra (wing covers) are actually fused together rendering this evil wee weevil flightless.  Another interesting facet of this beetles life is that it reproduces parthenogenetically. (no male required). In fact only females have been recorded.

3. Cupboard Spider

Cupboard Spider, Steatoda grossa. -  Lateral View  - (click to enlarge)
Cupboard Spider, Steatoda grossa. - Oblique  Dorsal View  (click to  enlarge)

While sorting out a large wooden box full of old blacksmith's tools I came across a relative of the infamous Redback spider Latrodectus hasseltii. It's known as the Cupboard Spider, Steatoda grossa. Like the weevil above, this is a cosmopolitan species but it is considered to be a native of Europe, including Britain.

Are they dangerous to humans? There is at least one well documented case of a  22-year-old female bitten on the shoulder by a Cupboard spider. She developed nausea, vomiting, and severe local and regional pain; symptoms similar to that  caused by the bite of Latrodectus spiders such as the Redback..  In fact, the symptoms were succesfully treated with Redback spider antivenom.

  • Common I.F.B. (1990) Moths of Australia - Melbourne University Press
  • Greenslade P., Farrow R. A., and Smith J. M. B. (1999). Long distance migration of insects to a subantarctic island. - Journal of Biogeography 26 , 1161–1167.
  • Graudins, Andis; Gunja, Narendra; Broady, Kevin W.; Nicholson, Graham M. (June 2002). "Clinical and in vitro Evidence for the Efficacy of Australian Red-back Spider (Latrodectus hasselti) Antivenom in the Treatment of Envenomation by a Cupboard Spider (Steatoda grossa)". - Toxicon (Case report) 40 (6): 767–75.
  • Gyeltshen, J. and A. Hodges. (2006, revised 2012) Fuller Rose Beetle, Naupactus godmanni (Crotch) (Insecta: Coleoptera: Curculionidae). - Entomology and Nematology. Florida Cooperative Extension Service. University of Florida IFAS. 

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