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Calliphoridae - Blow Flies

This website is dedicated to the identification and taxonomy of Calliphoridae (blow flies) and Mesembrinellidae in the Nearctic and Neotropical Regions including North America, Central America, South America and the West Indies. Blow flies belong to the two-winged flies (order Diptera) and the blow fly family Calliphoridae. Until recently, the Calliphoridae included the distinctive Neotropical subfamily Mesembrinellinae, but recent research suggests this subfamily should be elevated to the family level, Mesembrinellidae (Marinho, et al, 2016) which I have accepted. Thus, I’ve expanded this site to address both families. The blow fly and mesembrinellid families include a variety of species with larvae that feed on carrion (e.g. Calliphora, Lucilia, Phormia and Mesembrinella). They include several species that are important to forensic and medical entomologists. In the Nearctic Region, currently there are 5 subfamilies, 17 genera and 92 species of Calliphoridae known. Protocalliphora, is the largest genus in the region with 27 described species. In the Neotropical Region, the number of genera and species of calliphorids is unclear, but it is likely about equal to the number in the Nearctic Region. Several genera and species are shared between the regions, while some genera and numerous species are unique to the Neotropical Region. The family Mesembrinellidae has, at least 50 species, including several undescribed species. They are found only in tropical or subtropical areas of South America, Central America and southern Mexico. The blow fly family includes the 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 zones. Bird blow flies are not addressed further in this site, to learn more about the species of bird blow flies in Protocalliphora and Trypocalliphora go to my website birdblowfly.com. Links to pdfs of most of my publications in both websites 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 four recent publications (Whitworth 2006; Whitworth 2010; Tantawi & Whitworth 2014; and Tantawi, Whitworth, & Sinclair 2017). For Central and South America, I also published a revision of Calliphora and described one new species (Whitworth 2012) and I revised the Neotropical Lucilia and described six new species (Whitworth 2014). For Whitworth 2006, I recommend you use the revised version available herein, it contains updated keys which were completed in spring 2017. For other blow fly and mesembrinellid species in Central and South America, their taxonomy is much less settled and species identification is complicated by the presence of numerous undescribed species, especially in the Mesembrinellidae. Though there are a number of regional publications addressing the more common blow flies in the neotropics, there is still considerable confusion all the valid species there. Pioneering work on Neotropical species was conducted by Mello, Mariluis, and Dear, see the literature list for references. Much more taxonomic research is needed to clarify other genera and species in this region.

REQUEST FOR ASSISTANCE - - I am currently working on to the taxonomy of the Mesembrinellidae, I am especially interested in examining specimens of any mesembrinellids 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 with the identification of Nearctic blow flies. You can reach me at twhitworth@wsu.edu or blowfly@twhitworth.com

 

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, an earthworm parasite 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, blow fly. 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 and burrows into their flesh (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. To date, they are still considered a single 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, but a concerted control effort by USDA involving sterile male release eradicated this species from North America. Recently (spring 2017), however, it has been confirmed present in Florida where it appears to have begun reinvading the United States. 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 too. Species of bird blow flies (Protocalliphora and Trypocalliphora) are important parasites of altricial nestling birds (see bird blow fly website, birdblowfly.com).

The Mesembrinellidae generally appear different than blow flies, many in this family tend to be large and shining brown, yellow-brown, black or dark blue in color, they are often described as “testaceous”. Their most distinctive character is the posterior thoracic spiracle which is large and kidney-shaped. This family includes a number of genera, though some researchers believe the species could be consolidated into just a few genera. The reproductive system of females resembles those in Sarcophagidae in that they give live birth to a single larva at a time. The life cycle of this group is not clearly understood, adults of many species are attracted to carrion, larvae may be predaceous or feed on carrion or some have speculated they may be parasitic.

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 © 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.