Calliphoridae - Blow Flies with notes on Mesembrinellidae
This website is dedicated to the identification and taxonomy of Calliphoridae (blow flies) 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. See further discussion of Mesembrinellidae at the end of this section. The blow fly family includes a variety of species, some have larvae that feed on carrion, some cause myiasis and others are parasitic (e.g. Calliphora, Lucilia, Cochliomyia, Phormia and Protocalliphora). They include several species that are important to forensic and medical entomologists. In the Nearctic Region, currently there are 4 subfamilies, 14 genera and 79 species of Calliphoridae known. The subfamily Polleniinae (including six species of Pollenia and 8 species of Melanodexia) has recently been elevated to family status, thus the number of genera and species in Calliphoridae has been revised, from 5 subfamilies to 4 and from 93 species to 79 (Cerretti et al., 2019). Protocalliphora, is the largest genus in the Nearctic with 28 described species. In the Neotropical Region, the number of genera and species of calliphorids is unclear, there are likely still some undescribed species there, and some groups need revision, but the total 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 Nearctic and Neotropical Regions. The blow fly family includes the Holarctic bird blow fly genera Protocalliphora and Trypocalliphora; they are blood sucking 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, go to my website birdblowfly.com. Links to pdfs of my publications are available under Terry Whitworth publications. See the literature list for a list of many publications on blow flies and mesembrinellids.
The Mesembrinellidae generally appear different than blow flies, many species in this family are large and shining brown, yellow-brown, black or dark blue in color, they are often described as “testaceous” in appearance. Their most distinctive character is the posterior thoracic spiracle which is large and kidney-shaped (see fig. 7 Whitworth & Yusseff-Vanegas 2019). Until recently, this family included 9 genera, but based on the work of Marinho et al. (2017) and Whitworth & Yusseff-Vanegas (2019) only 3 genera are currently recognized and 5 genera are synonymized with Mesembrinella. Five species-groups were recognized by Whitworth & Yusseff-Vanegas within the genus Mesembrinella. The reproductive system of females resembles those in Sarcophagidae in that most species 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 family Mesembrinellidae, at this writing, has 53 known species plus several undescribed species (Whitworth & Yusseff-Vanegas 2019). They are known only from tropical or subtropical areas of South America, Central America and southern Mexico.
Any study of living organisms requires accurate species identification as an important first step. Our knowledge of blow fly species in North America is good, especially as a result of four recent publications (Whitworth 2006; Tantawi & Whitworth 2014; Tantawi, Whitworth, & Sinclair 2017; Jones, Whitworth, & Marshall 2019). For Central and South America, I published a review of blow flies of the West Indies and described one new species, I also revised the Calliphora of the neotropics and described one new species (Whitworth 2012) and revised the Neotropical Lucilia and described six new species (Whitworth 2014). For other blow fly genera and species in Central and South America, taxonomy is less settled and species identification is more complicated, several genera need revision. Though there are a number of regional publications addressing the more common blow flies in the neotropics, there is still some confusion about the valid species there. Pioneering work on Neotropical species was conducted by Mello, Mariluis, and Dear, see the literature list for references. More taxonomic research is needed to clarify other genera and species in this region. For the Mesembrinellidae, we revised this family and provide detailed keys and illustrations (Whitworth & Yusseff-Vanegas 2019).
REQUEST FOR ASSISTANCE - - I am currently working on to the taxonomy of the Mesembrinellidae and Neotropical blow flies, 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 |
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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 has occurred. The presence of large numbers of blow flies in structures usually indicates an animal has died in or under the structure.
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 website “bird blow fly.com” for further discussion). The term “blow” in the name blow fly refers to the habit of females of these flies “blowing” eggs on (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 wounds 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, Skoda et al. 2018), 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. Other species thought to be involved in myiasis include Lucilia elongata (Briggs, 1975) and L. silvarum (Bolek & Coggins, 2002 and Bolek & Janovy, 2004) in toads and frogs. I have identified the specimens examined for these studies and they all have proved to actually be L. bufonivora. Arias-Robledo et al. (2019) has recently concluded that L. silvarum is likely not a parasite, it is thought to be just saprophagous in Europe and I now believe that is true in North America too. I have found the poorly known L. elongata and L. thatuna primarily in marshy areas where amphibians abound, which suggests their larvae may also parasitize toads and frogs, but further research is need to confirm this. 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/ or http://www.forensicentomology.com/index.html |
