Root Borer from AustraliaD
Location: Australia
December 16, 2010 5:12 am
Dear bug man
I found these two bugs flying around. I think they are a type of root borer. What do you think? And do they bite?
Signature: Jess
Poinciana Longicorn
Hi Jess,
We believe we have correctly identified your Prionids, commonly called Root Borers, as the Poinciana Longicorn, Agrianome spinicollis, based on a photo posted to the Queensland Museum website. That site indicates: “This species is found in rainforest and open forest in eastern Australia. It is common in Queensland and New South Wales and also occurs on Lord Howe Island. The larvae are huge white grubs found in rotten wood, especially dead Poinciana or fig trees. It is an important pest of pecan trees. The large adults sometimes blunder into house lights.“ Graeme’s Insects of Townsville, Australia also has some nice photos of the Poinciana Longicorn. We found an online reference to an overlooked publication on Australian insects that has this information:
“The information provided noted that the large white grubs (larvae) of A. spinicollis tunnel into
trees and feed upon the wood and that large oval (exit) holes are often observed on the bark. The
species usually attacks dead timber but beetles are occasionally found in living trees feeding upon
the green wood (Anon., 1934). As they burrow through the wood, they close up the tunnel behind
them with the excreta being pressed into a hard mass with the posterior abdominal segment
(Anon., 1934). The eggs are placed upon the bark or wood of the tree; the tiny larvae hatch from
the eggs and immediately bore into the wood tissue; even at this stage, the mandibles are hard and
strong (Anon., 1934). During September and October the mature larvae cease feeding and a
gradual change occurs within their bodies; the larva contracts, the skin becomes loose and the
body becomes soft and flabby; the larva becomes a pre-pupa which lasts about 2 weeks (Anon.,
1934). The skin then splits along the back of the head and thorax and is gradually worked down
the length of the body by a series of convulsive movements and then cast off, revealing a pearly
white pupa (Anon., 1934). The pupa rests in its pupal chamber for about 2 months; after the
final metamorphosis occurs, the pupal skin is cast off and the adult beetle emerges and remains in
the wood for a few days before eating its way out of the tree (Anon., 1934).”
Regarding your bite question, Prionids have strong mandibles that they need to chew their way out of their pupal chambers when they mature. Large Prionids can deliver a painful bite that can draw blood, and they should be handled with caution.
Poinciana Longicorns
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