Major Group: Insecta
Order: Diptera
Family: Syrphidae
Subfamily: Eristalinae
Genus: Eristalis
Aquatic species of Syrphidae in Australia are represented by a single genus, Eristalis. |
Descriptive Features: posterior spiracles close together on a fused process - a short to long retractile tube
head capsule incomplete, reduced in size and structure, without externally visible sclerotization, retractile into thorax
maxillary palps and antenna small or absent
cephalic structure a "cephalopharyngeal" skeleton
mandibles usually with hooked apical tooth and lacking inner teeth, operating in ventral plane
abdomen 8-segmented
Total length: up to 30mm including tube
|
|
Eristalis larva |
|
|
|
Eristalis pupa |
|
Taxonomic Checklist: Species
Eristalis tenax Linnaeus
?Eristalis calida Walker
?Eristalis dubia Macquart
|
|
Distribution: Australia wide
Sensitivity Rating: SIGNAL grade 2
Functional Feeding Group: gathering collectors |
|
sewage outflow at Wonga Wetlands, Albury NSW |
|
|
Ecology: Instream habitat: Eristalis larvae occur in still and slow-flowing waters, often within highly polluted or low oxygen environments such as sewage. They are usually found in the sediment of shallow waters.
Feeding ecology: Larvae are gathering collectors feeding on animal and plant tissue in the sediment.
Habit: Eristalis larvae are commonly known as ‘rat-tailed maggots’ due to the telescopic breathing tube at the posterior end of the abdomen. This extendable ‘snorkel’ can stretch to the surface allowing syrphid larvae to breathe and survive in putrid water that lacks oxygen. Syrphid adults are swift fliers that typically hover, apparently motionless, in the air, giving rise to the common name of ‘hover-fly’.
Life history: Adult hoverflies mate near water in spring then the female lays her eggs singularly in shallow water. Eggs hatch after a few days. Larvae pass through a number of instars before they pupate. Pupation occurs during summer when the final instar larva crawls out of the water by twisting its body to move across the soil. The last larval skin forms the pupal cell. The adult breaks out of the pupal skin after approximately three weeks and flies away. |
| |
Information Sources: Colless & McAlpine 1991, Hawking & Smith 1997, Gooderham & Tsyrlin 2002, Evenhuis 2008, Wade et al. 2004
Key to Species: none |
|
|
|
