Worldwide, the Stiletto Flies (Insecta: Diptera: Asiloidea:Therevidae) have been poorly known and among the least understood of the flies (order Diptera). Diptera are among the poorest known of the larger insect orders. Yet this fascinating, medium-sized (>1,600 spp.) family of flies is critical to the sound functioning of arid and semiarid environments, including agroecosystems and forests in those zones. Individuals of this family have been infrequently collected because the adults are usually secretive, frequenting habitats rarely sampled by collectors.

The predaceous larvae are hidden within dry, friable, often sandy substrates. Consequently, larvae of these flies may well be excellent control agents of active fossorial arthropod pests in sandy agroecosystems. Furthermore, their abundance can be an indirect measure of subterranean productivity, and their diversity may be an excellent indicator of habitat heterogeneity.

Thereva fucata Loew larva
Thereva fucata Loew (Diptera: Therevidae) photo by M. E. Irwin

The Therevid PEET Program

Since the first National Science Foundation announcement of a special competition on Partnerships for Enhancing Expertise in Taxonomy (PEET) in 1995, five competitions, held every two years have awarded a total of 70 grants. They have been granted to researchers working on poorly known organisms, with an emphasis on training the next generation of systematists, and bringing their organisms into the electronic age through publications, databases, and websites.

The Therevid PEET project, Towards a World Monograph of the Therevidae (Insecta: Diptera) DEB-95-21925, was one of the first group of 21 projects funded for five years, starting 21 August 1995. The principal investigators on the grant, Michael E. Irwin, University of Illinois (UIUC); Brian Wiegmann, North Carolina State University (NCSU); David Yeates, University of Queensland (UQ), Australia each brought their own expertise and strengths to the project. They were joined by collaborators F. Chris Thompson, USDA-SEL based at the US National Museum of Natural History; Gail Kampmeier and Don Webb, Illinois Natural History Survey; J. Marie Metz, scientific illustrator at UIUC; Evert I. Schlinger, Schlinger Foundation; and graduate students Stephen GaimariMark MetzKevin Holston, and Martin Hauser, UIUC; Shaun Winterton, UQ; and Longlong Yang, NCSU.

When the project was renewed for a second five years (DEB-99-77958 from 21 August 2000-2005), PI Yeates had moved to CSIRO in Canberra, Australia and was joined by postdoc, Christine LambkinHilary Hill became a graduate student at NCSU. Throughout all, the project has been partnered by the institutions housing the scientists and the Schlinger Foundation, which funded numerous expeditions, students and hourly workers, and the scientific illustrator (see Sponsors below).

Until this project was funded by the NSF PEET program, the insect family Therevidae (Diptera: Asiloidea) had been among the poorest known and least understood of the flies worldwide. Therevids are collected infrequently because the predaceous larvae are hidden within dry, friable substrates, and adults are usually secretive, frequenting habitats rarely sampled by collectors. This medium-sized family of flies (4,000 species) is critical to the sound functioning of arid and semiarid environments, including agroecosystems and forests in those zones. Due to the ancient divergences of therevid taxa during the Jurassic and low propensity to long-distance dispersal, stiletto flies are excellent model organisms for addressing a variety of biogeographical questions – from those related to continental drift to island biogeography to local speciation.

The long-term project goal is to fashion a stable, predictive classification of stiletto flies (Diptera: Therevidae), comparing reconstructed phylogenies with historical geographies of associated land masses and determining the evolutionary placement of the family among other families of the Asiloidea.

Graduate students are the primary focus of the training component of this project, producing five Ph.D.s in systematics and dipterology, and four Masters degrees, two which then earned or will earn Ph.Ds in the program, one pursuing a Ph.D. elsewhere, and the fourth a Masters of Art Education. Over 35 students have been trained in databasing, and we have begun an internship program to train scientists in countries with severely threatened biota.

Because the scope and breadth in science and professional development are stressed, we have been fortunate to be able to invest heavily in fieldwork to instill graduate students with a foundation to interpret morphological, ecological, and behavioral characteristics of organisms in their environments. Expeditions were funded with matching funds from the Schlinger Foundation.

The keystone of information management for the project is Mandala™. The name “mandala” emphasizes the interwoven relationships underlying a suite of databases developed in FileMaker™ Pro. Specimens are tagged with unique numbers and identified by taxon name, which includes the history of the name, its use in the literature, misuse or changes, hierarchical classification, location of holotype, valid name, and synonymies. Also attached to specimen records is information about collecting locality, including latitude and longitude for use in biogeographic studies, conditions surrounding the collecting event, floral and faunal associations, collectors, determinations, illustrations, GenBank data, and the collection location where the specimen is and has been housed. Mandala is cross platform (Macintosh and Windows OS) and can be easily modified for use with other taxa.

Specimens are the basic building blocks for monographs. Over 100 museums and private collections have been combed for therevid material. Collections have been visited to study primary types and unsorted material. Huge taxon/geographic gaps in extant therevid material and the lack of well-preserved material for molecular studies have led to targeted expeditions over the course of the grants by various members of the therevid PEET team to Southwestern Europe, Australia, New Caledonia, New Zealand, Middle East, Africa, Madagascar, and the Americas. More than 111,000 specimens have been catalogued into Mandala from the expeditions and loans from museum.


Annual reports on the progress and activities of the Therevid PEET team were submitted to the National Science Foundation.

NSF PEET Grant – 1995-2000

NSF PEET Grant – 2000-2005

Sponsors of Therevid Research


Names or links to commercial products are for informational purposes only and do not constitute endorsement. Information contained on these pages may be preliminary, does not constitute publication, and may not be cited or published without express permission of individual authors or Michael E. Irwin.

Research cited in this report is supported in part by the National Science Foundation’s program on Partnerships for Enhancing Expertise in Taxonomy (PEET) Grants DEB-95-21925 and DEB-99-77958, the Schlinger Foundation, the University of Illinois, North Carolina State University, the University of Queensland, and the Illinois Natural History Survey.