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Calliphoridae - Blow Flies

This website is dedicated to the identification and taxonomy of blow flies in the Nearctic and Neotropical Regions including North America, Central America, South America and the West Indies. Blow flies are part of the two-winged flies (order Diptera) and blow fly family Calliphoridae. The blow fly family includes a variety of carrion feeding species (e.g. Calliphora, Lucilia, and Phormia) that are important to forensic and medical entomologists. It also includes bird blow flies (Protocalliphora and Trypocalliphora); they are bird nest parasites that are a major concern for birders and ornithologists in the northern hemisphere, especially in temperate areas. In the Nearctic Region there are about 17 genera and about 90 species of Calliphoridae, the largest genus in the region is Protocalliphora with 27 described species. In the Neotropical Region the number of genera and species is unclear, but it likely is about equal to the number in the Nearctic Region. In this region, there is confusion about which named genera and species are valid and there are likely a number of undescribed species. Several genera and species are shared between the regions, while some genera and numerous species are unique to the Neotropical Region. Bird blow flies are not addressed further in this site, to learn more about the bird blow flies Protocalliphora and Trypocalliphora go to my website birdblowfly.com. Links to pdf’s of most of my publications in both categories are available from my literature list.

Any study of living organisms requires accurate species identification as an important first step. Our knowledge of blow fly species in North America and the West Indies is good, especially as a result of two recent publications (Whitworth 2006, Whitworth 2010). The identity of most blow fly species in Central and South America is much less settled and identification is complicated by the presence of numerous undescribed species. Though there are a number of regional publications addressing the more common blow flies in South America, there is still considerable confusion about valid species in this region. Pioneering work on Neotropical species was conducted by Mello, Mariluis, and Dear, see the literature list for references. Whitworth (2012) has recently redescribed the Calliphora of the Neotropical Region which helps distinguish species in this genus. Much more taxonomic research is needed to clarify other genera and species in this region.

REQUEST FOR ASSISTANCE - I am currently working on keys to Neotropical Lucilia and the Mesembrinella group. I am especially interested in examining any blow flies from the Neotropical Region and will provide identifications at no charge. Any museums or individuals with unidentified blow flies from the Neotropical Region are invited to contact me about collaboration. I am also available to assist researchers needing assistance in the identification of Nearctic blow flies. You can reach me at twhitworth@wsu.edu.

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About Blow Flies

Blow flies are one of the most commonly seen insects around the world. Their relatively large size and gleaming green, blue, purple or coppery color is distinctive. They usually arrive quickly after an animal dies, especially if bleeding occurred. The presence of large numbers of blow flies in structures usually indicates an animal has died in or under the structure, although Pollenia often overwinters in structures.

Worldwide the blow fly family (Calliphoridae) includes over 1000 species and 150 genera (Rognes 1991). Blow fly species are found throughout all geographical regions of the world from the poles to the equator. You may see blow fly written as one word, blowfly or blow-fly, especially in Europe, but most entomologists agree it should be written as two words. Some common names for blow flies include bluebottle, greenbottle, black blow flies or carrion flies. Some species of blow flies invade live animal tissue causing myiasis and may be referred to as screwworm flies. There are old world screwworm flies (Chrysomya) and new world screwworm flies (Cochliomyia). The bird blow fly Trypocalliphora braueri also invades live tissue of nestling birds (see the bird blow fly section of this site for further discussion). Members of the earthworm parasite genus Pollenia are commonly called cluster flies. The term “blow” in the name blow fly refers to the habit of females of these flies “blowing” (depositing eggs or larvae on) dead carcasses or live hosts.

Some species of myiasis-causing blow flies are economically important because they lay eggs or larvae in injured areas on livestock (sometimes called blow fly strike). Larvae burrow into live tissue which can lead to serious injury or death of infested animals. For example, larvae of Lucilia cuprina kill or injure sheep in Australia costing farmers millions of dollars annually. In other parts of the world, this widespread species rarely behaves like those in Australia, suggesting they may actually be a different species. Until the late 1950’s or early 1960’s, Cochliomyia hominivorax (the primary new world screwworm fly) caused similar damage to livestock in North America. However a concerted control effort by USDA involving sterile male release eradicated this species from North America. This species is still found in parts of Central and South America where it attacks and often kills livestock and wildlife. Lucilia elongata and L. silvarum are known to cause myiasis in toads and frogs which can be lethal. I have found the poorly known L. thatuna primarily in marshy areas where amphibians abound, which suggests their larvae may also parasitize toads and frogs. Species of bird blow flies (Protocalliphora and Trypocalliphora) are important parasites of altricial nestling birds (see bird blow fly website, birdblowfly.com).

The general public’s interest in blow flies has increased recently with the popularity of television programs such as CSI where blow flies and other insects activity is used to estimate minimum time since death in possible crime victims. Forensic entomologists are experts at using insects collected at crime scenes to provide physical evidence to help recreate events associated with a crime.  Surprisingly, most working forensic entomologists are not too happy about the fictional use of forensics shown in TV programs. They find that many jurors in real murder trials often expect clear, definitive proof of guilt in murder cases just like it is done on TV. In the real world, guilt is usually based on a preponderance of evidence and not some silver bullet that proves “who done it”, as nice as that would be. To learn more about Forensic Entomology from the experts visit http://www.nafea.net/ and http://www.forensicentomology.com/index.html

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Terry Whitworth, Ph.D.
Entomologist
2533 Inter Avenue
Puyallup, WA 98372
Phone 253-845-1818
email: twhitworth@blowflies.net

all content copyright © 2012 by Terry L Whitworth except as noted. site design by flashpoint design
Portions of images by Joseph Berger (blowfly in header), and Whitney Cranshaw (fly on wall), used by permission of www.insectimages.org.