Exotic snails were much easier to find, a mildly interesting record being Vitrina pellucida (see 2002 Tasmanian 
Naturalist). 
Also, a bristletail (juvenile Machiloides) was collected and a pseudoscorpion and two large earwig species 
photographed. 
Invertebrates [Lynne Forster] 
Some encounters with species undergoing potential biological control provided interesting experiences 
during the walk. 
Gorse, a weed of national significance, was our first victim. Colonies of gorse spider mite ( Tetranychus 
lintearius) webs encased spiny gorse branches in white shrouds from which they eat the leaves. It is 
because they spin webs that they are called ‘spider mites’ though until now I had not appreciated how 
extensive their webbing abilities could be when they combine their efforts. Their small red bodies 
speckled the webs which also contained white remains from previous moults. The mites were introduced 
into Tasmania to control gorse ( Ulex europaeus) in 1998. Predation by the introduced Chilean predatory 
mite, Phytoseiulus persimilis and the native coccinellid, Stethorus histrio , has reduced numbers of the 
mites (Ireson et al, 2003). At the base of the gorse bushes were other dense webs but these had circular 
entrance holes belonging to an Amaurobioides sp. spider that was not the expected species, A. maritimus 
( =litoralis ). 
Near the Spit dam swarms of horehound stink bugs, Agonoscelis rutila (Hemiptera: Pentatomidae) 
attracted us to the noxious weed Marrubium vulgare commonly known as horehound. The native orange 
and black bugs are typically found in clusters on horehound during winter where they suck sap from the 
plant but do not affect the weed’s vigour. In summer the bugs disperse to eucalypts and other native 
species. Horehound is originally from the Egyptian desert extending to some parts of Europe, and was 
introduced as a medicinal herb and for beer brewing (Weiss and Sagliocco, 2000). One wonders where 
the bugs over-wintered prior to its introduction and how the ecology of the bugs might have changed 
following the arrival of horehound in Tasmania. Horehound is known to contain diterpenes (Knoss et al , 
1997) which are natural insecticides, so the bugs would be likely to sequester these compounds for 
defence. Terpenes and phenols are also available from eucalypt and other native plant species (Cooper, 
2001 ). 
Horehound taints the flesh of sheep that graze upon it, though sheep eat it as a last resort, while the burrs 
cause felting of fleece (DPIPWE, 2008). The pale horehound plume moth, Wheeleria spilodactylus, 
(Lepidoptera: Pterophoridae) was first released in Tasmania by TIAR in 1997 at Sorell to control 
horehound (Ireson et al , 2000). The moth, whose larvae eat leaves, has four generations per year (Wills, 
2000). We did not see any moths but photographed a lone caterpillar of the species on the ground near the 
shore. 
List of invertebrate species (found mostly in the coastal strip just above high tide): 
Beetles 
-Adoryphorous couloni (Scarabaeidae) on the beach at mid tide mark. These native, black, shiny, 
cockchafers feed on grass roots and are appearing on many beaches and city streets at this time of the 
year, having emerged from over-wintering underground. 
-Mandalotus sp nr vascillans (Curculionidae) clustered under rocks on bare earth near the dam. 
- Saragus costatus (Tenebrionidae) pie-dish beetle 
- Sclerorhinus bubalis (Curculionidae: Amycterinae) large weevil 
Spiders 
-Steatoda grossa (Theridiidae) near the shore under rocks- dark with purplish brown abdomen and pale 
semicircle line anterior abd and blotchy pale spots 
-Venatrix esposica (Lycosidae) wolf spider under a large rock with remains of several meals - it was 
particularly fond of pie-dish beetles, large weevils and the occasional snail, Theba pisana. 
-Laperousea quindecimpunctata Linyphiidae under rocks near the shore on fine, small sheet webs 
-beach jumping spider (Salticidae) on sand at high tide mark 
Tasmanian Field Naturalists Club BULLETIN 336 Oct 2009 p6 
