Historic weevil

I first published this story back in April 2015. Recently, I spoke about this weevil on ABC Radio Ballarat and also at a talk I gave to Friends of the Grampians Gariwerd (FOGG) so I thought now is a good time to republish.

I found this fellow trundling along the road when I went for my morning walk the other day. This insect is commonly known as a Botany Bay weevil (Chrysolopus spectabilis) or by its other common name “diamond weevil”. This is the male of the species. Females are larger insects, making males the lesser of two weevils (sorry, I couldn’t resist!).

Botany Bay weevilBotany Bay weevils belong to an historic group of insects. This weevil was collected by Sir Joseph Banks on Captain James Cook’s voyage to Australia in 1770. Actually we don’t know that Banks himself collected it – it could have been one of his men, or the Swedish naturalist Daniel Solander who accompanied Banks on the voyage. On his return, Banks gave the task of cataloguing his insect collection to the Danish insect taxonomist Johann Fabricius. The weevil was described in 1775, making it one of the first (if not the first) Australian insects described to western science.

Sydneysiders may be surprised to learn that the Botany Bay weevil is not only found around Sydney, but from coastal far north Queensland to eastern South Australia. The weevil is certainly common in New South Wales and its common name probably dates back to the early colonial days of Botany Bay.

To this day we don’t actually know where Banks’ specimen was collected. Was the weevil collected at Botany Bay in April 1770, or during July/August 1770 when Cook was repairing the Endeavour near present day Cooktown, or at one of the other landing points in between? The label on the specimen simply says “nova Hollandia”.

Botany bay weevil femaleBotany Bay weevils are associated with about 30 species of Acacia. Female weevils chew holes in stems at or below ground level in which they lay their eggs. Upon hatching the larvae bore into the stem and usually down into the roots. Adult weevils emerge in the summer, and what spectacular insects they are with their rich metallic green or blue markings on a black background. The adult weevils also feed on Acacia spp. in their characteristic manner of removing the leading shoots several centimetres down the stem.

The Botany Bay weevil has a distinctive defence mechanism. One day I was taking some close-up images of weevils on Acacia provincialis when I got just a bit too close for comfort. The weevil suddenly went stiff, toppled backwards and fell to the ground like an actor in a B grade Western movie. The trick I learned was to move closer to them slowly, taking photos as I went, so they got used to me and the noise of the camera.

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Cottony scales

There are about 80 species of ‘soft scale’ insects of the family Coccidae found in Australia. The ones I find most interesting are the pulvinariine soft scales which are known colloquially as ‘cottony scales’, ‘cottony soft scales’ and (my favourite) ‘cushion bears’. These common names help to describe the cottony egg sacs (ovisacs) of adult female scales. The image below shows adult female Pulvinaria dodonaeae on the leaves of a species of Myoporum.

Cottony soft scaleThe insect itself is brown in colour and the ovisac is the furrowed white mass behind. Pulvinaria dodonaeae is endemic to Australia and is not considered to be a pest. Its species name, dodonaeae, coveniently indicates some of its host plants are within the plant genus Dodonaea. One of the exotic (i.e introduced from elsewhere) cottony soft scales found in Australia goes by the name of Pulvinaria hydrangeae. Can you guess which plant it occurs on? Continue reading Cottony scales

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Sex, gender & difference

Men are from Mars and women are from Venus or so the saying goes. However the anatomical differences between male and female humans are relatively minor when compared to the differences between male and female insects.

“Why is this ‘ant’ attacking a ‘fly’ via its ovipositor?” an insect enthusiast asked me in an email recently (the insects in question can be seen below). The image clearly illustrates sexual dimorphism. My Dictionary of Entomology, a massive tome only owned by insect nerds like me, defines sexual dimorphism as ‘differences in size, shape, anatomical features, colour or behaviour between males and females of a species’.

Flower wasp Continue reading Sex, gender & difference

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Stingers

Jack Jumper ant
Ouch!! I felt a sharp stabbing pain on the webbing between two fingers of my left hand. I looked down to see a Jack Jumper ant gripping my skin tightly with its mandibles and burying its sting in my flesh. I had been winding a hose back on its reel, the ant had taken a ride on the hose, became caught in my hand and went into attack mode. Ever been stabbed by hot needles? That’s what it feels like. Continue reading Stingers

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Return of the Green Scarab

Green scarab beetleDuring November swarms of green scarab beetles (Diphucephala colaspidoides) descended on my place. They are notorious leaf eaters noted for stripping the leaves from a variety of plants. The beetles tend to feed in large groups so plant damage can happen quickly and be quite devastating. Can plants recover after such damage? Continue reading Return of the Green Scarab

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