Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Datasheet

Cochliomyia hominivorax
(New World screwworm)

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Datasheet

Cochliomyia hominivorax (New World screwworm)

Summary

  • Last modified
  • 19 November 2019
  • Datasheet Type(s)
  • Invasive Species
  • Preferred Scientific Name
  • Cochliomyia hominivorax
  • Preferred Common Name
  • New World screwworm
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Metazoa
  •     Phylum: Arthropoda
  •       Subphylum: Uniramia
  •         Class: Insecta
  • Summary of Invasiveness
  • Cochliomyia hominivorax (Coquerel) is endemic to the Western Hemisphere, with the exception of Chile., although it has been eradicated from significant parts of its range. Although naturally occurring in relati...

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Pictures

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PictureTitleCaptionCopyright
Screwworm - Screwworm myiasis in a calf navel.
TitleExternal symptoms
CaptionScrewworm - Screwworm myiasis in a calf navel.
Copyright©USDA-2002/Foreign Animal Diseases Training Set/USDA-Animal and Plant Health Inspection Service (APHIS)
Screwworm - Screwworm myiasis in a calf navel.
External symptomsScrewworm - Screwworm myiasis in a calf navel.©USDA-2002/Foreign Animal Diseases Training Set/USDA-Animal and Plant Health Inspection Service (APHIS)
Adult female screwworm fly.
TitleAdult
CaptionAdult female screwworm fly.
Copyright©USDA-2002/Foreign Animal Diseases Training Set/USDA-Animal and Plant Health Inspection Service (APHIS)
Adult female screwworm fly.
AdultAdult female screwworm fly.©USDA-2002/Foreign Animal Diseases Training Set/USDA-Animal and Plant Health Inspection Service (APHIS)
Screwworm. Third instar larvae of Cochliomyia hominivorax.
TitleScrewworm larvae
CaptionScrewworm. Third instar larvae of Cochliomyia hominivorax.
Copyright©USDA-2002/Foreign Animal Diseases Training Set/USDA-Animal and Plant Health Inspection Service (APHIS)
Screwworm. Third instar larvae of Cochliomyia hominivorax.
Screwworm larvaeScrewworm. Third instar larvae of Cochliomyia hominivorax.©USDA-2002/Foreign Animal Diseases Training Set/USDA-Animal and Plant Health Inspection Service (APHIS)

Identity

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Preferred Scientific Name

  • Cochliomyia hominivorax Coquerel

Preferred Common Name

  • New World screwworm

Other Scientific Names

  • Calliphora hominivorax (COQUEREL)
  • Callitroga americana (CUSHING & PATTON)
  • Callitroga hominivorax
  • Cochliomyia americana
  • Lucilia hominivorax

International Common Names

  • English: flies, screwworm; Primary screwworm; screw worm; screwworm; screwworms in livestock
  • Spanish: Gusano Barrenador del Ganado
  • French: lucilie bouchere; ver en vis
  • Portuguese: bicheira

Local Common Names

  • Aruba: Schroefworm
  • Germany: Fliege, Schraubenwurm-
  • Netherlands Antilles: Schroefworm

EPPO code

  • COCLAM (Cochliomyia americana)
  • COCLHO (Cochliomyia hominivorax)

Summary of Invasiveness

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Cochliomyia hominivorax (Coquerel) is endemic to the Western Hemisphere, with the exception of Chile., although it has been eradicated from significant parts of its range. Although naturally occurring in relatively low numbers compared with other insect species, C. hominivorax has been introduced and spread into non-endemic and eradicated areas via movement of infested hosts, including humans. Introductions of C. hominivorax, sometimes resulting in outbreaks, have occurred in the United States of America, Mexico, Panama, Curacao, Aruba, Libya, and Australia.

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Metazoa
  •         Phylum: Arthropoda
  •             Subphylum: Uniramia
  •                 Class: Insecta
  •                     Order: Diptera
  •                         Family: Calliphoridae
  •                             Genus: Cochliomyia
  •                                 Species: Cochliomyia hominivorax

Notes on Taxonomy and Nomenclature

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The taxonomy and nomenclature of this species was very confused for over 100 years. Cushing and Patton (1933) documented the difference between Cochliomyia americana C & P and Cochliomyia macellaria Fabricius, which served as a key basis in the eradication of Cochliomyia hominivorax from North America, Central America and parts of the Caribbean. Dear (1985) presents an explanation of the taxonomy and nomenclature of C. hominivorax and other members of the Chrysomyini.

Distribution

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Cochliomyia hominivorax is endemic to the Western Hemisphere and occurs in tropical, subtropical, and temperate zones. Northern and southern limits of its range are primarily due to cold weather. Cochliomyia hominivorax is present in all South American countries with the exception of Chile. This species is also present in Cuba, the Dominican Republic, Haiti, Jamaica, and Trinidad and Tobago. Cochliomyia hominivorax has been eradicated from the United States of America, Mexico, Guatemala, Belize, Honduras, El Salvador, Nicaragua, Costa Rica, and Panama (an outbreak in Florida in 2016 was eradicated in 2017). A barrier zone is maintained in Panama using sterile flies and field operations to prevent immigration of C. hominivorax into eradicated areas. Eradication has also been achieved in Curacao, Netherlands Antilles, British Virgin Islands, US Virgin Islands, and Puerto Rico.

Distribution Table

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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Last updated: 05 Mar 2020
Continent/Country/Region Distribution Last Reported Origin First Reported Invasive Reference Notes

Africa

AlgeriaAbsent, No presence record(s)OIE (2009)
AngolaAbsent, No presence record(s)OIE (2009)
BotswanaAbsent, No presence record(s)OIE (2009)
BurundiAbsent, No presence record(s)OIE Handistatus (2005)
CameroonAbsent, No presence record(s)OIE Handistatus (2005)
Central African RepublicAbsent, No presence record(s)OIE Handistatus (2005)
Congo, Democratic Republic of theAbsent, No presence record(s)OIE Handistatus (2005)
Côte d'IvoireAbsent, No presence record(s)OIE Handistatus (2005)
DjiboutiAbsent, No presence record(s)OIE (2009)
EgyptAbsent, No presence record(s)OIE (2009)
EthiopiaAbsent, No presence record(s)OIE (2009)
KenyaAbsent, No presence record(s)OIE (2009)
LesothoAbsent, No presence record(s)OIE (2009)
LibyaAbsent, Eradicated19921988FAO (1992)
MadagascarAbsent, No presence record(s)OIE (2009)
MauritiusAbsent, No presence record(s)OIE (2009)
MoroccoAbsent, No presence record(s)OIE (2009)
MozambiqueAbsent, No presence record(s)OIE (2009)
NigeriaAbsent, No presence record(s)OIE (2009)
RwandaAbsent, No presence record(s)OIE (2009)
São Tomé and PríncipeAbsent, No presence record(s)OIE Handistatus (2005)
SeychellesAbsent, No presence record(s)OIE Handistatus (2005)
South AfricaAbsent, No presence record(s)OIE (2009)
SudanAbsent, No presence record(s)OIE (2009)
TunisiaAbsent, No presence record(s)OIE (2009)
ZambiaAbsent, No presence record(s)OIE (2009)
ZimbabweAbsent, No presence record(s)OIE (2009)

Asia

ArmeniaAbsent, No presence record(s)OIE (2009)
AzerbaijanAbsent, No presence record(s)OIE (2009)
BahrainAbsent, No presence record(s)OIE (2009)
BangladeshAbsent, No presence record(s)OIE (2009)
BhutanAbsent, No presence record(s)OIE (2009)
ChinaAbsent, No presence record(s)OIE (2009)
GeorgiaAbsent, No presence record(s)OIE Handistatus (2005)
IndiaAbsent, No presence record(s)OIE (2009)
IndonesiaAbsent, No presence record(s)OIE (2009)
IranAbsent, No presence record(s)OIE (2009)
IraqAbsent, No presence record(s)OIE (2009)
IsraelAbsent, No presence record(s)OIE (2009)
JordanAbsent, No presence record(s)OIE (2009)
KazakhstanAbsent, No presence record(s)OIE (2009)
KuwaitAbsent, No presence record(s)OIE (2009)
KyrgyzstanAbsent, No presence record(s)OIE (2009)
LaosAbsent, No presence record(s)OIE (2009)
LebanonAbsent, No presence record(s)OIE (2009)
MalaysiaAbsent, No presence record(s)OIE (2009)
-Peninsular MalaysiaAbsent, No presence record(s)OIE Handistatus (2005)
-SabahAbsent, No presence record(s)OIE Handistatus (2005)
-SarawakAbsent, No presence record(s)OIE Handistatus (2005)
MyanmarAbsent, No presence record(s)OIE (2009)
North KoreaAbsent, No presence record(s)OIE Handistatus (2005)
OmanAbsent, No presence record(s)OIE (2009)
PakistanAbsent, No presence record(s)OIE (2009)
Saudi ArabiaAbsent, No presence record(s)OIE (2009)
SingaporeAbsent, No presence record(s)OIE (2009)
South KoreaAbsent, No presence record(s)OIE (2009)
Sri LankaAbsent, No presence record(s)OIE (2009)
SyriaAbsent, No presence record(s)OIE (2009)
TaiwanAbsent, No presence record(s)OIE Handistatus (2005)
TajikistanAbsent, No presence record(s)OIE (2009)
TurkeyAbsent, No presence record(s)OIE (2009)
TurkmenistanAbsent, No presence record(s)OIE Handistatus (2005)
United Arab EmiratesAbsent, No presence record(s)OIE (2009)
UzbekistanAbsent, No presence record(s)OIE Handistatus (2005)
VietnamAbsent, No presence record(s)OIE (2009)

Europe

AlbaniaAbsent, No presence record(s)OIE (2009)
AndorraAbsent, No presence record(s)OIE Handistatus (2005)
BelgiumAbsent, No presence record(s)OIE (2009)
Bosnia and HerzegovinaAbsent, No presence record(s)OIE Handistatus (2005)
BulgariaAbsent, No presence record(s)OIE (2009)
CroatiaAbsent, No presence record(s)OIE (2009)
CyprusAbsent, No presence record(s)OIE (2009)
CzechiaAbsent, No presence record(s)OIE (2009)
DenmarkAbsent, No presence record(s)OIE (2009)
EstoniaAbsent, No presence record(s)OIE (2009)
FinlandAbsent, No presence record(s)OIE (2009)
FranceAbsent, No presence record(s)OIE (2009)
GermanyAbsent, No presence record(s)OIE (2009)
GreeceAbsent, No presence record(s)OIE (2009)
HungaryAbsent, No presence record(s)OIE (2009)
IcelandAbsent, No presence record(s)OIE (2009)
IrelandAbsent, No presence record(s)OIE (2009)
Isle of ManAbsent, No presence record(s)OIE Handistatus (2005)
ItalyAbsent, No presence record(s)OIE (2009)
JerseyAbsent, No presence record(s)OIE Handistatus (2005)
LatviaAbsent, No presence record(s)OIE (2009)
LiechtensteinAbsent, No presence record(s)OIE (2009)
LithuaniaAbsent, No presence record(s)OIE (2009)
LuxembourgAbsent, No presence record(s)OIE (2009)
MaltaAbsent, No presence record(s)OIE (2009)
MoldovaAbsent, No presence record(s)OIE Handistatus (2005)
MontenegroAbsent, No presence record(s)OIE (2009)
NetherlandsAbsent, No presence record(s)OIE (2009)
North MacedoniaAbsent, No presence record(s)OIE (2009)
NorwayAbsent, No presence record(s)OIE (2009)
PolandAbsent, No presence record(s)OIE (2009)
PortugalAbsent, No presence record(s)OIE (2009)
RussiaAbsent, No presence record(s)OIE (2009)
SerbiaAbsent, No presence record(s)OIE (2009)
Serbia and MontenegroAbsent, No presence record(s)OIE Handistatus (2005)
SlovakiaAbsent, No presence record(s)OIE (2009)
SloveniaAbsent, No presence record(s)OIE (2009)
SpainAbsent, No presence record(s)OIE (2009)
SwedenAbsent, No presence record(s)OIE (2009)
SwitzerlandAbsent, No presence record(s)OIE (2009)
UkraineAbsent, No presence record(s)OIE (2009)
United KingdomAbsent, No presence record(s)OIE (2009)
-Northern IrelandAbsent, No presence record(s)OIE Handistatus (2005)

North America

BarbadosAbsent, No presence record(s)OIE Handistatus (2005)
BelizeAbsent, Eradicated1994Wyss (2000); OIE (2009)
BermudaAbsent, No presence record(s)OIE Handistatus (2005)
British Virgin IslandsAbsent, Eradicated1975Wyss (2000); OIE Handistatus (2005)
CanadaAbsent, No presence record(s)OIE (2009)
Cayman IslandsAbsent, No presence record(s)OIE Handistatus (2005)
Costa RicaAbsent, Eradicated2000Wyss (2000); OIE (2009)
CubaPresentOIE (2009)
CuraçaoAbsent, Eradicated1954Wyss (2000); OIE Handistatus (2005)
DominicaAbsent, No presence record(s)OIE Handistatus (2005)
Dominican RepublicPresentOIE (2009)
El SalvadorPresentOIE (2009); Wyss (2000)
GreenlandAbsent, No presence record(s)OIE (2009)
GuadeloupeAbsent, No presence record(s)OIE (2009)
GuatemalaAbsent, Eradicated1994Wyss (2000); OIE (2009)
HaitiPresentOIE (2009)
HondurasAbsent, Eradicated1996Wyss (2000); OIE (2009)
JamaicaPresentOIE (2009)
MexicoAbsent, Eradicated1991Wyss (2000); OIE (2009)
Netherlands AntillesAbsent, Eradicated1954Wyss (2000); CABI Data Mining (2001)
NicaraguaAbsent, Eradicated1999Wyss (2000); OIE (2009)
PanamaAbsent, No presence record(s)OIE (2009); CABI (Undated)
Puerto RicoAbsent, Eradicated1975Wyss (2000)
Saint Kitts and NevisAbsent, No presence record(s)OIE Handistatus (2005)
Saint Vincent and the GrenadinesAbsent, No presence record(s)OIE Handistatus (2005)
Trinidad and TobagoPresentOIE Handistatus (2005)
U.S. Virgin IslandsAbsent, Eradicated1975Williams et al. (1977); CABI Data Mining (2001)
United StatesAbsent, Eradicated1966Wyss (2000); OIE (2009)
-FloridaAbsent, Eradicated20171933Skoda et al. (2018)Originally introduced in 1930s; eradicated by 1959; outbreak in 2016 eradicated in 2017

Oceania

AustraliaAbsent, No presence record(s)OIE (2009)
French PolynesiaAbsent, No presence record(s)OIE (2009)
New CaledoniaAbsent, No presence record(s)OIE (2009)
New ZealandAbsent, No presence record(s)OIE (2009)
SamoaAbsent, No presence record(s)OIE Handistatus (2005)
VanuatuAbsent, No presence record(s)OIE Handistatus (2005)

South America

ArgentinaPresentOIE (2009)
BoliviaAbsent, Unconfirmed presence record(s)OIE (2009)
BrazilPresentOIE (2009)
-Mato Grosso do SulPresentCABI Data Mining (2001)
-Minas GeraisPresentCABI Data Mining (2001)
-Rio de JaneiroPresentCABI Data Mining (2001)
-Rio Grande do SulPresentCABI Data Mining (2001)
-Sao PauloPresentCABI Data Mining (2001)
ChileAbsent, No presence record(s)OIE (2009)
ColombiaPresent, WidespreadForero B. et al. (2008); OIE (2009)
EcuadorPresent, LocalizedOIE (2009)
Falkland IslandsAbsent, No presence record(s)OIE Handistatus (2005)
French GuianaAbsent, No presence record(s)OIE (2009)
GuyanaPresent, WidespreadGrant et al. (2000); CABI (Undated)
ParaguayPresentOIE Handistatus (2005)
PeruAbsent, Unconfirmed presence record(s)OIE (2009)
SurinamePresent, WidespreadGrant et al. (2000)
UruguayPresentOIE (2009)
VenezuelaPresent, WidespreadCoronado and Kowalski (2009)

Introductions

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Introduced toIntroduced fromYearReasonIntroduced byEstablished in wild throughReferencesNotes
Natural reproductionContinuous restocking
Aruba 2004 Yes No Eradicated 2004; JB Welch, USDA, unpublished data
Aruba 2011 Yes No Eradicated 2011; JB Welch, USDA, unpublished data
Curaçao 1971-1977 Yes No Baumhover (1997) Eradicated 1977
Libya 1988-1992 Animal production (pathway cause) Yes No FAO (1992) Eradicated 1992
Mexico 1992 Yes No Wyss (2000) Eradicated 1992
Mexico 1993 No No Wyss (2000) Eradicated 1993
Mexico 2001 Yes No Eradicated 2001; JB Welch, USDA, unpublished data
Mexico Mexico 2003 No No Introduced due to irradiator malfunction; eradicated 2003; JB Welch, USDA, unpublished data
Panama Mexico 2003 No No Introduced due to irradiator malfunction; eradicated 2003; JB Welch, USDA, unpublished data
Panama 2012 No No Eradicated 2012; JB Welch, USDA, unpublished data
Panama 2009 Yes No Eradicated 2009; C Duerr, COPEG, unpublished data
Florida 2016 No No Skoda et al. (2018) Eradicated 2017

Risk of Introduction

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Risk of introduction of C. hominivorax may be relatively low; however, movement of infested hosts into non-infested habitats remains a risk. As long as populations of C. hominivorax exist in the Western Hemisphere, modern travel conveyances, especially aircraft, make the introduction of C. hominivorax continents away from the original source of infestation a real possibility. Adults of C. hominivorax can occasionally enter cars, boats, ships, and aircraft, but this is extremely rare.

Pathogen Characteristics

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Detailed descriptions of the life stages of C. hominivorax are presented in Laake et al. (1936).

Eggs: Eggs are bright white, approximately 1.04 mm long and 0.26 mm in diameter with a cylindrical shape, rounded at the posterior end and flattened at the anterior end with a dorsal seam extending from the anterior end almost to the posterior end of the egg. Eggs are laid in a parallel pattern in layers glued together to form a mass which gives them the appearance of a shingled roof. Eggs are laid in masses which contain from 10 to 400. Eggs are generally laid on or near the edges of wounds but may also be laid on or near host body orifices with purulent discharge. Eggs have also been observed laid approximately 5 cm from the edge of wounds under the moist wool of sheep in Costa Rica during the rainy season (J Welch, personal observation).

Larvae: First instar larvae are approximately 1.2 mm and 0.23 mm, length and diameter, respectively, at hatching and are clear with internal structures visible. Mature first instar larvae are approximately 3.6 mm and 0.57 mm, length and diameter, respectively, and are whitish in colour. Newly molted second instar larvae are generally whitish in colour and are approximately 3.5mm and 0.6mm, length and diameter, respectively. Mature second instar larvae are approximately 6.3 mm to 7.4 mm and 1.5 mm, length and diameter, respectively, and are whitish to cream coloured. Third instar larvae are white to cream to pink coloured depending on diet, and are approximately 6.4 mm to 17 mm in length and 1.6 mm to 3.5 mm in diameter. All larval instars have characteristic bands of spines on most segments and a pair of heavily sclerotized mouth hooks, main tracheal trunks and spiracles. The spiracles with three slit-like openings are almost completely surrounded by heavily sclerotized peritremes, but which appear incomplete ventrally.

Pupae: Pupae are barrel-shaped and dark brown in colour. They are approximately 10.2 mm and 4.3 mm in length and width, respectively.

Adults:Laake (1936) reported that flies are generally deep metallic greenish-blue in colour. Colour is variable, ranging from metallic light to dark green, light grayish-blue through sky-blue to dark blue (J Welch, personal observation). Flies have three dark longitudinal stripes on the dorsal part of the thorax. C. hominivorax adults are approximately 2-3 times the size of a house fly.

List of Symptoms/Signs

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SignLife StagesType
General Signs / Cyanosis, blue skin or membranes Sign
General Signs / Inability to stand, downer, prostration Sign
General Signs / Swelling mass penis, prepuce, testes, scrotum Sign
Nervous Signs / Dullness, depression, lethargy, depressed, lethargic, listless Sign
Pain / Discomfort Signs / Skin pain Sign
Reproductive Signs / Paraphimosis or priapism, inability to retract penis Sign
Reproductive Signs / Phimosis Sign
Skin / Integumentary Signs / Alopecia, thinning, shedding, easily epilated, loss of, hair Sign
Skin / Integumentary Signs / Foul odor skin, smell Sign
Skin / Integumentary Signs / Parasite visible, skin, hair, feathers Sign
Skin / Integumentary Signs / Skin erythema, inflammation, redness Sign
Skin / Integumentary Signs / Skin necrosis, sloughing, gangrene Sign
Skin / Integumentary Signs / Skin ulcer, erosion, excoriation Sign
Urinary Signs / Dysuria, difficult urination, stranguria Sign

Climate

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ClimateStatusDescriptionRemark
A - Tropical/Megathermal climate Preferred Average temp. of coolest month > 18°C, > 1500mm precipitation annually
Af - Tropical rainforest climate Preferred > 60mm precipitation per month
Am - Tropical monsoon climate Preferred Tropical monsoon climate ( < 60mm precipitation driest month but > (100 - [total annual precipitation(mm}/25]))
As - Tropical savanna climate with dry summer Tolerated < 60mm precipitation driest month (in summer) and < (100 - [total annual precipitation{mm}/25])
Aw - Tropical wet and dry savanna climate Tolerated < 60mm precipitation driest month (in winter) and < (100 - [total annual precipitation{mm}/25])
C - Temperate/Mesothermal climate Tolerated Average temp. of coldest month > 0°C and < 18°C, mean warmest month > 10°C
Cf - Warm temperate climate, wet all year Preferred Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year
Cs - Warm temperate climate with dry summer Tolerated Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers
Cw - Warm temperate climate with dry winter Tolerated Warm temperate climate with dry winter (Warm average temp. > 10°C, Cold average temp. > 0°C, dry winters)

Latitude/Altitude Ranges

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Latitude North (°N)Latitude South (°S)Altitude Lower (m)Altitude Upper (m)
41°58’ 38°03’

Air Temperature

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Parameter Lower limit Upper limit
Absolute minimum temperature (ºC) -6.67
Mean annual temperature (ºC) 19.4
Mean minimum temperature of coldest month (ºC) 9.4

Rainfall

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ParameterLower limitUpper limitDescription
Mean annual rainfall152mm; lower/upper limits

Rainfall Regime

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Summer
Uniform
Winter

Natural enemies

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Natural enemyTypeLife stagesSpecificityReferencesBiological control inBiological control on
Araneae Predator Adults not specific
Eriophora ravilla Predator
Formicidae Predator Larvae not specific
Macrocheles muscaedomesticae Parasite
Neoscona oaxacensis Predator
Nephila clavipes Predator
Trichotrombidium muscarum Parasite

Notes on Natural Enemies

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Cochliomyia hominivorax occurs in relatively low numbers compared with other insect species. Populations are aggregated yet mobile within favourable habitats. As a result, no natural enemies specific for C. hominivorax have been identified. Other insects, birds, frogs, lizards and spiders feed on adult C. hominivorax.Welch (1993) describes the predation of ground-released sterile C. hominivorax flies by spiders. Ants (especially Solenopsis sp.) are common predators of larvae that have exited wounds to pupate and have been observed pulling larvae from wounds (J Welch, unpublished data). There are no data to suggest that natural enemies are important to the population dynamics of C. hominivorax.

Pathway Causes

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CauseNotesLong DistanceLocalReferences
AidVery low risk Yes Yes
Animal productionModerate risk with movement of infested animals Yes Yes
HitchhikerVery low risk Yes Yes
Hunting, angling, sport or racingVery low risk by movement of infested hunting dogs Yes Yes
Intentional releaseLow risk Yes Yes
Military movementsVery low risk Yes Yes
People foragingVery low risk Yes Yes
Pet tradeVery low risk Yes Yes

Pathway Vectors

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VectorNotesLong DistanceLocalReferences
AircraftLow risk, but possible Yes Yes
Bulk freight or cargoVery low risk, but possible Yes Yes
Hides, trophies and feathersVery low risk Yes Yes
Land vehiclesVery low risk, but possible Yes
LivestockModerate risk Yes Yes
Pets and aquarium speciesWarm-blooded terrestrial pets Yes Yes

Economic Impact

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Myiasis by C. hominivorax results in a negative economic impact by a decrease in animal weights and milk production, and an increase in animal death. Additionally increase in the costs of inspection and handling of animals, and the increase in costs of insecticides, and veterinary services and medicines results in a negative economic impact (Wyss, 2000). Wyss (2000) reported substantial annual economic benefits to producers (US$ with conversion to 2015 US$ in parentheses) after eradication of C. hominivorax; $896.1 million ($1.25 billion) for the United States of America, $328.6 ($458.5) million for Mexico, and $87.8 ($122.5) million for all of the Central America countries combined. Expanding the analysis of the economic impact of eradicating C. hominivorax from Central America by adding linkages to the economy and consumer benefits resulted in an estimated total annual economic impact of $704.3 ($982.6) million to consumers (Wyss, 2000). Wyss (2002) estimated the annual economic benefits to producers in South America as $2.8 ($3.91) billion.

Environmental Impact

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Impact on habitats is none or unknown.

Impact on biodiversity is low, but may become more important in localized areas during conditions which promote the increase of C. hominivorax populations. Fuller (1962) reported that mortality of fawns of White-tailed deer, Odocoileus virginianus (Zimmerman), ranged from 20 to 80 percent annually depending on environmental and population conditions.

Social Impact

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Infestation of humans is under-reported due to the negative social implications. Those humans who cannot take care of themselves are especially vulnerable. Although the young, old, and mentally challenged are more susceptible to myiasis, all humans are potential hosts. Humans living in areas of favorable habitats for C. hominivorax are at a higher risk than those living in unfavorable habitats.

Risk and Impact Factors

Top of page Invasiveness
  • Invasive in its native range
  • Proved invasive outside its native range
  • Has a broad native range
  • Abundant in its native range
  • Pioneering in disturbed areas
  • Tolerant of shade
  • Capable of securing and ingesting a wide range of food
  • Highly mobile locally
  • Benefits from human association (i.e. it is a human commensal)
  • Fast growing
  • Has high reproductive potential
Impact outcomes
  • Damaged ecosystem services
  • Ecosystem change/ habitat alteration
  • Host damage
  • Increases vulnerability to invasions
  • Negatively impacts agriculture
  • Negatively impacts cultural/traditional practices
  • Negatively impacts human health
  • Negatively impacts animal health
  • Negatively impacts livelihoods
  • Reduced amenity values
  • Reduced native biodiversity
  • Threat to/ loss of endangered species
  • Threat to/ loss of native species
  • Damages animal/plant products
  • Negatively impacts trade/international relations
Impact mechanisms
  • Parasitism (incl. parasitoid)
  • Pathogenic
  • Rapid growth
Likelihood of entry/control
  • Difficult to identify/detect as a commodity contaminant
  • Difficult to identify/detect in the field
  • Difficult/costly to control

Gaps in Knowledge/Research Needs

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Research is needed on:

1.     Population dynamics and distribution of C. hominivorax in the Amazon Basin.

2.     Development of an attractant for male C. hominivorax.

3.     Development of a new wound-treatment as coumaphos is no longer being produced.

References

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Baumhover AH, 1963. Susceptibility of screwworm larvae and prepupae to dessication. Journal of Economic Entomology, 56:473-475.

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Forero B E, Cortés V J, Villamil J L, 2008. The problem of screwworm, Cochliomyia hominivorax (Coquerel, 1858), in Colombia. (Problemática del gusano barrenador del Ganado, Cochliomyia hominivorax (Coquerel, 1858) en Colombia.) Revista MVZ Cordoba, 13(2):1400-1414. http://apps.unicordoba.edu.co/revistas/revistamvz/mvz-132/v13n2a16.pdf

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Laake EW, Cushing EC, Parish HE, 1936. Biology of the Primary Screw Worm Fly, Cochliomyia americana, and a Comparison of its Stages with those of C. macellaria. Technical Bulletin. United States Department of Agriculture, 500. 24 pp.

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OIE Handistatus, 2004. World Animal Health Publication and Handistatus II (data set for 2003). Paris, France: Office International des Epizooties.

OIE Handistatus, 2005. World Animal Health Publication and Handistatus II (data set for 2004). Paris, France: Office International des Epizooties.

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Osorio J, Moncada L, Molano A, Valderrama S, Gualtero S, Franco-Paredes C, 2006. Role of ivermectin in the treatment of severe orbital myiasis due to Cochliomyia hominivorax. Clinical Infectious Diseases, 43(6):e57-e59. http://www.journals.uchicago.edu/CID/journal/home.html

Parker FD, Welch JB, 1992. Monitoring adult populations of the screwworm (Diptera: Calliphoridae) with feeding stations baited with liver. Journal of Economic Entomology, 85(5):1740-1753.

Parker FD, Welch JB, Matlock RB, 1993. Influence of habitat, season, and attractant on adult behavior of the screwworm (Diptera: Calliphoridae) in a tropical dry zone in Costa Rica. Journal of Economic Entomology, 86(5):1359-1375.

Parman DC, 1945. Effect of Weather on Cochliomyia americana and a Review of Methods and economic Applications of the Study. 66-76 pp.

Phillips PL, Welch JB, Kramer M, 2004. Seasonal and spatial distributions of adult screwworms (Diptera: Calliphoridae) in the Panama canal area, Republic of Panama. Journal of Medical Entomology, 41(1):121-129.

Skoda, S. R., Phillips, P. L., Welch, J. B., 2018. Screwworm (Diptera: Calliphoridae) in the United States: Response to and Elimination of the 2016–2017 Outbreak in Florida, Journal of Medical Entomology, 55 https://doi.org/10.1093/jme/tjy049

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Williams DL, Gartman SC, Hourrigan L, 1977. Screwworm eradication in Puerto Rico and the Virgin Islands. World Animal Review, No. 21:31-35.

Wyss JH, 2000. Screw-worm eradication in the Americas - overview. In: Area-wide control of fruit flies and other insect pests. Joint proceedings of the international conference on area-wide control of insect pests, 28 May-2 June, 1998 and the Fifth International Symposium on Fruit Flies of Economic Importance, Penang, Malaysia, 1-5 June, 1998 [ed. by Tan, K. -H.]. Pulau Pinang, Malaysia: Penerbit Universiti Sains Malaysia, 79-86.

Wyss JH, 2002. Overview of the sterile insect technique in screw-worm fly eradication. In: Proceedings of the screw-worm fly emergency preparedness conference, Canberra, Australia, 12-15 November 2001. Canberra, Australia: Agriculture, Fisheries, and Forestry, 176-181.

Distribution References

CABI Data Mining, 2001. CAB Abstracts Data Mining.,

CABI, Undated. Compendium record. Wallingford, UK: CABI

Coronado A, Kowalski A, 2009. Current status of the New World screwworm Cochliomyia hominivorax in Venezuela. Medical and Veterinary Entomology. 23 (s1), 106-110. http://www.blackwell-synergy.com/loi/mve DOI:10.1111/j.1365-2915.2008.00794.x

FAO, 1992. The new world screwworm eradication programme North Africa 1988-1992., Rome, Italy: FAO. 192 pp.

Forero B E, Cortés V J, Villamil J L, 2008. The problem of screwworm, Cochliomyia hominivorax (Coquerel, 1858), in Colombia. (Problemática del gusano barrenador del Ganado, Cochliomyia hominivorax (Coquerel, 1858) en Colombia.). Revista MVZ Cordoba. 13 (2), 1400-1414. http://apps.unicordoba.edu.co/revistas/revistamvz/mvz-132/v13n2a16.pdf

Grant G H, Snow J W, Teran M V, 2000. The New World screw-worm as a pest in the Caribbean and plans for its eradication from Jamaica and the other infested Caribbean islands. In: Area-wide control of fruit flies and other insect pests. Joint proceedings of the international conference on area-wide control of insect pests, 28 May-2 June, 1998 and the Fifth International Symposium on Fruit Flies of Economic Importance, Penang, Malaysia, 1-5 June, 1998. [ed. by Tan K -H]. Pulau Pinang, Malaysia: Penerbit Universiti Sains Malaysia. 87-93.

OIE Handistatus, 2005. World Animal Health Publication and Handistatus II (dataset for 2004)., Paris, France: Office International des Epizooties.

OIE, 2009. World Animal Health Information Database - Version: 1.4., Paris, France: World Organisation for Animal Health. https://www.oie.int/

Skoda SR, Phillips PL, Welch JB, 2018. Screwworm (Diptera: Calliphoridae) in the United States: Response to and Elimination of the 2016-2017 Outbreak in Florida. In: Journal of Medical Entomology, 55 https://doi.org/10.1093/jme/tjy049

Williams D L, Gartman S C, Hourrigan L, 1977. Screwworm eradication in Puerto Rico and the Virgin Islands. World Animal Review. 31-35.

Wyss J H, 2000. Screw-worm eradication in the Americas - overview. In: Area-wide control of fruit flies and other insect pests. Joint proceedings of the international conference on area-wide control of insect pests, 28 May-2 June, 1998 and the Fifth International Symposium on Fruit Flies of Economic Importance, Penang, Malaysia, 1-5 June, 1998. [ed. by Tan K -H]. Pulau Pinang, Malaysia: Penerbit Universiti Sains Malaysia. 79-86.

Links to Websites

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WebsiteURLComment
COPEG, Panama–United States Commission for the Eradication and Prevention of Screwwormhttp://www.copeg.org/
Food and Agriculture Organization of the United Nationshttp://www.fao.org/
IAEA, International Atomic Energy Agencyhttp://www.iaea.org/
US Dept of Agriculture - APHIShttp://www.aphis.usda.gov/
World Organisation for Animal Health (OIE)http://www.oie.intWebsite of the World Organisation for Animal Health (formerly Office International des Epizooties).

Organizations

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World: OIE (World Organisation for Animal Health), 12, rue de Prony, 75017 Paris, France, http://www.oie.int/

Panama: COPEG (Panama-United States Commission for the Eradication and Prevention of Screwworm), http://www.copeg.org/

Austria: IAEA (International Atomic Energy Agency), Vienna International Centre, PO Box 100, A-1400 Vienna, http://www.iaea.org/

Italy: FAO (Food and Agriculture Organization of the United Nations), Viale delle Terme di Caracalla, 00100 Rome, http://www.fao.org/

USA: USDA-APHIS (Animal and Plant Health Inspection Service), US Department of Agriculture 1400, Independence Ave., SW Washington, DC 20250, Washington, DC, USA, http://www.aphis.usda.gov/

Contributors

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27/01/16 Original text by:

John B. Welch, USDA-APHIS-IS, USDA-ARS-SPARC, 2881 F&B Road, College Station, Texas, USA

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