Skevington, J.H., Young A.D., Thompson, F.C
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Entomological Society of Queensland NEWS BULLETIN Price $3.50 Print Post Approved 100001946 Volume 42, Issue 8, November 2014 Natural history and systematics of flower flies (Diptera: Syrphidae) Jeffrey H. Skevington (Fig. 1), Andrew D. Young (Fig. 2) and F. Christian Thompson entomophiles as the dominant Flower flies or hover flies are outback flower fly. They arguably the most important family abound wherever there are of Diptera pollinators. Over 6000 flowers and can be found species of flower flies have been throughout even the most arid described but in Australia the fauna parts of Australia. Chris is rather poorly studied with only Lambkin and Susan Wright 163 species known. Our work shows described five litres of Focks that at least 141 additional Malaise trap samples from undescribed species exist in Western Australia that were collections and we will endeavour to stuffed with Simosyrphus describe these over the next few Figure 1. Jeffrey H. grandicornis and little else after years. The genera Psilota, Skevington (JHS). Photo only a few days of collecting. Hemilampra, Triglyphus and Angela Skevington Waves of these flies lift off from possibly Eumerus are in most dire flowers in the outback during need of revision. Psilota alone includes over 70 peak season. The larvae of these flies are Australian species despite having only 14 typical of most Syrphinae and feed on aphids described. In order to complete revisions of and other soft-bodied Hemiptera. these groups, we have identified all of the syrphids in the major Australian collections Although most species of syrphids are flower (Australian Museum, Australian National visitors and easily detected in these situations, Insect Collection, Queensland Department of some species are Agriculture, Fisheries and Forestry Collection, rare, and are Queensland Museum, South Australian more easily found Museum, Victorian Agricultural Insect on hilltops. Collection and the Victorian Museum). We Hilltopping is a have databased most of these specimens (over common 15,000) and will continue to work through phenomenon other collections over the next two or three amongst insects years. that are either rare or have The Australian fauna is most diverse in the unpredictable coastal areas and only a few genera food supplies (i.e. (Simosyrphus and Eumerus in particular) have whenever it is been successful at colonizing the drier parts of difficult to find a the country. Simosyrphus grandicornis (Fig. 3) mate). Males of Figure 2. Andrew D. Young. in particular should be known to all hilltopping Photo Jeff Skevington Volume 42, Issue 8, November 2014 139 genus and with better resources; many will be identifiable to species. Good keys are lacking for Australia but will be produced as part of our project. Excellent keys and even field guides are available for some parts of the world. For example, we recently published an image-rich generic key to Nearctic syrphid genera (Fig. 5; http:// www.biology.ualberta.ca/bsc/ ejournal/mylmst_23/ mylmst_23.html) and a new Figure 3. Simosyrphus grandicornis Photo Andrew Young field guide to the hover flies of species go to landmarks and wait there until Britain by Stuart Ball and females arrive in search of a mate. The Roger Morris shows how syrphids can be made landmarks are typically the summits of hills as accessible to those interested as can birds. but openings in the forest, single trees, and We are in the final throws of completing a other obvious features will suffice for some comprehensive field guide to northeastern species or in some circumstances. During our North American Syrphidae (http:// fieldwork on syrphids, we therefore divide our www.canacoll.org/Diptera/Staff/Skevington/ time between searching flowers and hilltops. In Syrphidae/Syrphidae.htm) and envision Australia, several genera are more often found something like this for Australian syrphids hilltopping than in any other situation. In within the next decade. particular, Asiobaccha, Austalis, Cyphipelta, Eumerus, Meliscaeva, Psilota and Triglyphus There are currently four subfamilies of are all more regularly collected on hilltops than syrphids recognized. The typical yellow and in other situations. These species can be black-banded Syrphinae that should be familiar abundant on some hilltops while seemingly to gardeners worldwide constitute about one absent from all other areas. For example, JHS third of the world’s fauna. These typically collected dozens of an undescribed species of imperfect mimics (that look like wasps but Asiobaccha from a hilltop near Kinkin, have no specific wasp models) are ubiquitous Queensland despite seeing none in surrounding and conspicuous and virtually all are flower areas. Similarly, Cyphipelta rufocyanea (Fig. 4) is common on Mt. Coot-tha (trunk sitting at the summit) but is rarely seen in the surrounding forest. As an interesting side-note, JHS and his family collected several Cyphipelta at a hilltop in the Grampions (Reeds Lookout, Grampions National Park, Victoria) and at various hilltops in Tasmania that were behaving differently (hovering in the open) and are likely an undescribed species. Most syrphids can be easily field-identified to Figure 4. Cyphipelta rufocyanea. Photo Michael Jefferies Entomological Society of Queensland 140 Figure 5. Nearctic Generic key title page visitors and important pollinators as adults. gamut of Diptera larval ecological roles, from Larvae are usually predators of soft-bodied bacterial filter-feeding, to root and stem boring, Hemiptera such as aphids and scales but the to predation. The group includes the familiar more we get to know about larvae, the more rat-tailed maggot that is included in all exceptions there are. We now know of syrphine introductory biology texts. These larvae live in larvae that are aquatic predators in bromeliads aquatic environments where they filter feed on (Ocyptamus wulpianus), predators of adult flies bacteria. A long respiratory siphon give them attracted to whitefly colonies (Ocyptamus sp.), their familiar shape and allow them to breath leaf miners (Allograpta centropogonis), and from their tail end while their mouthparts are pollen feeders (Toxomerus politus). The suspended well below the water’s surface. subfamily Pipizinae is very divergent in adult Shorter-tailed versions exist that pierce plant morphology from syrphines (small black flies stems to breath (e.g. Chrysogaster hirtella). that look more like Eristalinae) but their larvae The eristalines include the only known pests in are similar and feed on root aphids and the family; most of them plant feeders. For psyllids. The huge paraphyletic subfamily example, Merodon equestris has been spread Eristalinae includes most of the large showy around the world and feeds on bulbs of syrphids. Many of them are pollinators, but Narcissus and relatives. Merodon and their some never visit flowers and can be very bulb feeding relatives (Portevinia and difficult to detect by both hand collecting and Eumerus) have their centre of diversity in the Malaise trapping. The larval habits of this Mediterranean region where bulb plants are subfamily are diverse and virtually cover the also most diverse. Despite this, Eumerus have Volume 42, Issue 8, November 2014 141 done well in Australia and are represented by at least eight species. Most are presumably bulb feeders but exceptions have been discovered. For example, Eumerus superbus (Fig. 6) feeds on female cycad flowers, a considerable ecological jump. A number of these ecological leaps have occurred in Australia and more will undoubtedly be discovered as we better document the larval life history of syrphids. A spectacular ecological jump has occurred in the Australian Ceriana. Most of the Figure 6. Eumerus superbus. Photo Andrew Young world’s Ceriana species feed on bacteria in sap runs under the bark of dead or dying research is going into the impact of syrphids in trees. At least one Ceriana species in Australia, agro-ecosystems. Some syrphids have been C. ornata (Fig. 7), has moved into native bee used commercially in greenhouses. In colonies where they feed on the comb, eggs particular, Eristalis tenax (Fig. 8) is used to and larvae. They are considered a pest and can pollinate sweet peppers. The natural control of decimate colonies that they gain access to. aphids, scales and other pests is almost impossible to quantify but some syrphids have The remaining syprhid subfamily is the been explored for biological control of invasive Microdontinae. Microdontines are often called pests. There is considerable potential here, in ant flies and all known are associated with ants particular with invasive plant control by as larvae. Most have been documented as Cheilosia species. Some syrphid larvae are predators within ant nests, disguising impressive consumers of waste and may be themselves by mimicking ant pheromones and used for rapid composting of organic waste. further protecting themselves with a hard outer Ornidia obesa has been explored for this in covering. The larvae are bizarre isopod-like Costa Rica and along with the stratiomyid, animals and have been described as molluscs Hermetia illucens, they can turn dump truck on at least five occasions (including their loads of orange pulp and peels into soil in days. earliest description!) Recently, a parasitoid was Current research in Spain has shown that some discovered in the group – Hypselosyrphus eristaline syprhids (Eristalinus aeneus for trigonus is a parasitoid of ant pupae. With only example) are hugely important in cleaning up 8% of microdontine life histories known, and a sewage lagoons as well as pig and olive farm wealth of undescribed species still to be runoff. The larvae filter feed on bacteria and discovered, parasitoidism may be much more can number in the billions in lagoons. This common than ever imagined in the group. research will be extended to Australia in 2015. Based on this summary of syrphid larval life In order to better predict which syrphids will histories, it is easy to see that these flies are of have the largest ecological impact we not only considerable economic importance.