The Mediterranean Fruit Fly

The Mediterranean fruit fly (Ceratitis capitata), commonly called Medfly, or Moscamed in Spanish, is one

of the world's most destructive agricultural pests.

The female Medfly attacks ripening fruit, piercing

the soft skin and laying eggs in the puncture. The

eggs hatch into larvae (maggots) that feed inside the

fruit pulp and renders the fruit inedible.

Appearance and Life Cycle

The adult Medfly is slightly smaller than a common

housefly and is very colorful. It has dark blue eyes, a

shiny, black thorax (back), and a yellowish abdomen

with silvery cross bands. Its wings, normally drooping, display a blotchy pattern with yellow, brown, and

black spots and bands.

The life cycle of the Medfly has five phases:

• The adult female deposits eggs under the skin of 

fruit, 

• The eggs hatch and produce maggots or wormlike larvae,

• The larvae feed on the pulp of fresh fruits and 

vegetables before dropping to the ground, where 

the larvae burrows into the soil,

• The larvae transform into pupae in the soil, and

• The pupae mature into adults and emerge from 

the soil.

Under tropical summer weather conditions, the

Medfly completes its life cycle in 21 to 30 days.

History

The Medfly originated in Africa. It has since spread

throughout the Mediterranean region, southern

Europe, the Middle East, Western Australia, South

and Central America, and Hawaii. In general, it is

found in most tropical and subtropical areas of the

world.

The Medfly became established in Hawaii in 1910.

Hawaii remains infested with this pest, and no eradication program is currently under way. The first of

numerous U.S. mainland infestations occurred in

Florida in 1929.

The Exotic Fruit Fly Strategic Plan

In January 2006, the U.S. Department of Agriculture’s

(USDA) Animal and Plant Health Inspection Service

(APHIS) released its plan to further protect the health

and value of American agricultural resources threatened by the introduction and establishment of exotic

fruit fly pests.

The agency’s Exotic Fruit Fly Strategic Plan harmonized all exotic fruit fly programs, including

Mediterranean, Mexican,and Oriental fruit flies.

Using an integrated, multi-faceted approach that

incorporates surveillance activities, control programs

and regulatory actions, State and Federal officials

can more effectively respond to a pest that attacks

more than 400 host plants. The plan sets five priorities:

• Preventing individual fruit fly introductions from 

becoming established populations

• Reducing the imminent threat of introduction or 

spread of Med- and Mexfly populations from 

existing populations in Mexico

• Mitigating the impact of fruit flies presently 

established in portions of the United States

• Encouraging the development of exotic fruit fly 

detection and management programs in the 

Caribbean Basin and Central America to act as 

an early warning system and further reduce the 

risk of introduction

• Providing technical support to reduction activities 

worldwide to further reduce the risk of fruit fly 

entry

Eradication

When fertile adults or larvae of Medflies are

detected in the continental United States, every effort

is made to eradicate the infestation as quickly as

possible. The area around the detection is treated

with a mixture of insecticide and bait to reduce or

eliminate the adult stage of the insect. Along with the

bait treatment, additional traps are placed in the field

to delineate the extent of the infestation. After the

bait-treatment schedule is completed, sterile Medflies

are released in and near the treatment zone to interrupt the breeding cycle. Once enough time has

elapsed for three generations of the insects to have

matured, if a local survey discloses no Medflies, the

area is declared once again free of the pest.

Survey

The USDA–APHIS along with State departments

of agriculture, maintains trapping programs in highrisk areas of States susceptible to Medfly establishment. When one or more wild Medflies are collected

in an area, APHIS and State officials immediately

begin a delimiting survey. Using the detection site as

the focal point, field crews position additional traps to

determine if an infestation exists and to locate and

define the limits of the infested area.
Regulation

If an infestation exists, Federal and State quarantine regulations are imposed to help prevent spread of

the pest by humans or vehicles. Federal quarantine

laws regulate the interstate movement of any article

that may harbor the fly. State regulations control the

movement of these articles going to uninfested areas

of the same State. Articles regulated by State and

Federal authorities include all Medfly-host fruits and

vegetables present in the area. Open-air fruit and

vegetable stands must provide protective covers for

the produce to prevent infestation. Commercial and

homegrown produce may not be moved without special inspection, treatment, and certification.

Control

Three kinds of treatment are used alone or in combination to eradicate the Medfly:

• Aerial and ground bait spray application. This 

treatment is approved for use by the U.S.

Environmental Protection Agency. The spray

contains minimal amounts of an insecticide and a 

protein/sugar bait that attracts the flies.

• Sterile insect technique (SIT). In the SIT, Medflies 

are reared in large quantities, sterilized with a 

small amount of irradiation, and released from 

airplanes into areas where they mate with wild 

Medflies. Such matings do not produce offspring.

Eventually the wild population is eliminated 

through attrition.

SIT is most effective against low-level Medfly populations where a high proportion of sterile to wild flies

can be achieved to ensure success. Initial applications of insecticide bait spray are sometimes necessary to bring local populations down to low densities.

• Insecticide application to soil under host trees.

Application of insecticides to the soil is used only 

when larvae are detected. These products will kill 

some larvae as they enter the soil to pupate and 

most of the adults as they later emerge.

The preferred and most popular eradication strategy is an integrated approach combining all three treatments, with emphasis on the use of SIT.

Damage

In the United States, the Medfly could attack peaches,

pears, plums, apples, apricots, avocados, citrus, cherries, figs, grapes, guavas, kumquats, loquats, nectarines, peppers, persimmons, tomatoes, and several

nuts.

If the Medfly were to become established, consumer prices would go up and produce would become

less available. In addition, backyard gardens, as well

as commercial production areas, would require

increased use of pesticides on a routine basis.

APHIS estimated the U.S. market value of the commodities that could host exotic fruit flies at about $7.2

billion in 2002. That dollar figure is the sum of damage to the economy from export sanctions, lost markets, treatment costs, reduced crop yields, deformities, and premature fruit drop.

The Medfly in Mexico and Guatemala

In 1977, the Governments of the United States,

Mexico, and Guatemala began a cooperative effort

known as the Moscamed Program to eradicate the

Medfly from Mexico and to maintain a barrier in

Guatemala to halt the Medfly’s northern spread. This

program is designed to suppress Medfly populations

and reduce the risk of introduction into the United

States.

The Moscamed Program operates two facilities

that produce sterile Medflies—one in Metapa de

Dominguez, Mexico, and one in El Pino, Guatemala.

Mexico has been free of Medfly since 1982, except

for the southernmost State of Chiapas, adjacent to

Guatemala. Occasionally, people transport the pest

north, causing outbreaks in border towns. In

September 2004, Medflies were found in a Tijuana,

Mexico, municipality. In a cooperative effort, Mexican

and U.S. agricultural officials eradicated the infestation

by March 2005.

Keeping the Medfly Out

Many of the insects, weeds, and plant diseases that

attack U.S. crops are foreign invaders. APHIS administers agricultural quarantine laws to help keep foreign

plant pests and diseases out and to control domestic

pests and diseases of limited distribution.

Travelers returning to the continental United States

from Hawaii or a foreign country are prohibited from

bringing into the country fresh fruits, meats, plants,

birds, and plant and animal products that may harbor

pests or diseases.

Additional Information

If you have questions about the Medfly, call the central

office of APHIS’ Plant Protection and Quarantine

(PPQ) unit at (301) 734–8645, or contact a U.S.

Federal regulatory official, listed in the Federal

Government section of your telephone directory under

USDA, APHIS, PPQ.

You may also call your State’s regulatory officials,

usually listed under department of agriculture, plant

protection or regulatory division, in the State government section of your telephone directory.

In addition, APHIS’ Internet home page

(http://www.aphis.usda.gov) provides up-to-date information on various agricultural pests and diseases and

other related topics.

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