Tasmania's Largest Beetles 
Simon Fearn 
T asmania has a large and diverse beetle fauna, 
many of which are rarely seen by casual 
observers. The three 'giants' fall into this category 
because, although they are all widespread and 
locally abundant, some knowledge of their life 
cycles and habits is required to reliably see them 
in the wild. 
Two of these species are long horn beetles in the 
sub-family Prioninae within the family 
Cerambycidae. Apart from a very few exceptions, 
Prionid long horn beetles are known for their 
great size and rather sombre overall colouring of 
various shades of brown and black. They include 
the largest of all beetles, the aptly named Titanus 
gigonteus of northern Brazil and the Guyana 
which attains a head/body length of 170 mm. All 
Prionid larvae are wood borers in both live and 
dead timber. 
Tasmania's two largest beetles are both Prionid 
long horns. The largest is Paroplites australis 
which infests large adult Banksia marginata 
throughout the warmer coastal regions of 
Tasmania as well as large parts of the northern 
midlands. The most dense populations I have 
seen are in the banksia-rich north east. Very 
rarely, large adult sh e-oaks (Allocasuarina strict a) 
are also utilised as food plants. These beetles are 
responsible for the destruction (usually through 
wind damage) or death of all large mature B. 
marginata within their range, and inspection of 
any dead trees reveals up to hundreds of large 
oval adult emergence holes in the bark and 
interiors heavily compromised by the boring 
activities of the finger sized larvae. This process 
under natural conditions is mitigated by banksia 
sapling regrowth. However, in some parts of the 
midlands, sheep grazing, and thus little or no 
sapling regrowth, has resulted in local extinctions 
of large mature trees. 
Paroplites australis can attain 55 mm in length 
with males typically being longer and more heavy 
limbed than females. Adults emerge all at once on 
hot, humid nights in late January and Febuary. 
Top left. A pair of Paroplites australis. The male is on the right. Note ovipositer protruding from the tip of 
the female P. australis abdomen. 
Top right. A pair ofToxeutes arcuatus. The female is on the left. 
Bottom. Two specimens of Hydrophilus latipalpus. 
Tasmanian Field Naturalists Club BULLETIN 341 January 2011 p7 
