Cooperative Extension Service 
Institute of Food and Agricultural Sciences
Hendry County Extension, P.O. Box 68, LaBelle, Florida 33975-0068  Phone (863) 674-4092

Hendry County Horticulture News

MedFly - One Bad Bug

There has been a lot of publicity recently about the Medfly following recent discoveries of the pest in several areas of the state.  The Mediterranean fruit fly or Medfly is one of the most destructive insect pests in the world. It attacks many fruits, nuts, and vegetables commonly grown by Florida homeowners and farmers. The Medfly could devastate agriculture. If it were to become established in the Florida, the Medfly would ravage commercial agriculture and make it difficult and expensive for you to grow fruits, nuts and vegetables in your backyard.  State and federal agricultural officials are mandated to keep the Mediterranean fruit fly out of this country.

The medfly is not just a citrus problem.   Medflies attack over 250 fruits, nuts, and vegetables including: tomato, pepper, eggplant, avocado, mango, persimmon, guava, pear, peach, apple, fig and many others. Countries with Medfly populations typically have crop losses of 25-50%. Total loss of affected crops can occur.  Florida crops potentially affected  by the Medfly bring $10 billion a year to the state. If that revenue were lost, every citizen would have to pay an extra $700 in taxes to maintain our quality of life.

Medflies are foreign pests to the continental U. S. They are usually spread into new areas by people carrying infested fruit. People cause Medfly infestations when they bring or mail un-inspected fruits, nuts, vegetables or plants from foreign or domestic quarantine areas to uninfected areas of the United States. If you live in or travel through a Medfly quarantine area, please: Don't give away, mail, or accept home-grown host fruits and vegetables, such as citrus, tomato, pepper, eggplant, fig, grape, mango, avocado, loquat, guava, papaya, and Surinam cherry. Canned, baked, frozen or preserved foods are safe.   Don't move potted plants grown under host plants unless they are first inspected. Medfly pupae may be hiding in the soil. Do not compost discarded host plants ­ they may be infested with Medflies, and the composting may not kill the pest. Double-bag and seal unwanted fruits and vegetables and discard with your trash. Cooperate with quarantine rules and allow inspectors access to your property to check plants or traps for infestations.

The Mediterranean fruit fly ( Ceratitis capitata) is smaller than a house fly. The top of its back is mottled with yellowish-white and black areas. The abdomen has two distinct white cross bands. The front edge of the wing has many small dark/clear areas. The Caribbean fruit fly (Anastrepha suspensa) is about the same size as the common house fly. The body is uniformly brownish yellow in color with no stripes or other patterns. The front edge of the wing is darkened except for a small clear area half way to the tip. When the Caribbean fruit fly invaded Florida in 1965, no eradication program was implemented. Today, many popular fruits, particularly papaya, peaches, guava, Surinam cherry and loquat, are ruined by Caribfly maggots.

Females puncture host fruits, nuts and vegetables and lay eggs. Larvae hatch from the eggs within 3 days under ideal conditions.  Maggots feed and grow in the host, usually causing early fruit drop. Larvae burrow into the soil where they change into pupae. After 10-11 days, the adult fly emerges. The complete Medfly life cycle is 20-30 days during warm months and up to 60 days in cooler months. The adult fly usually lives about 6 weeks but can survive up to a year. One female Medfly usually lays about 300 eggs in her lifetime, but may lay as many as 800.

State and federal officials utilize an integrated pest management approach in their efforts to completely eradicate the Medfly from the state.  These IPM strategies include:

Fruit Removal:
Ground and Aerial Treatments with malathion
Use of Sterile Flies:

Despite public concern, malathion is one of the safest insecticides, often used in food processing and preparation areas, grain silos, homes and offices. Over 60,000 gallons of malathion are used against mosquitos in Florida each year. Malathion protects pets from fleas in pet collars and flea dips. Sunlight and water destroy malathion in hours, so it does not "bioaccumulate." Breakdown happens very fast in Florida because of heat and humidity.

The low dose bait mixture poses little risk to humans. Humans have an enzyme that rapidly destroys malathion.  Studies by the National Cancer Institute have not shown malathion to cause cancer.  The vast majority of scientists agree that malathion, as it is used in the Medfly eradication program, poses no significant threat to public health. No significant adverse health effects on humans have been seen after previous aerial eradication programs.

Butterflies, ants and some beneficial insect populations will decrease, but they will recover rapidly from nearby local populations. If a local Medfly infestation spreads to a wider range of the state, more pesticide will be used, and insects will need more time to recover. Malathion has little toxicity to birds and mammals.

If the medfly is not eradicated, it will spread throughout Florida and eventually invade other states. Consumers could expect food prices to increase. Many backyard fruits and vegetables would be maggot-ridden and unfit to eat. Contributions of Florida agriculture to employment, taxes and quality of life in Florida would be greatly reduced. Homeowners and farmers will be forced to use more pesticide to try to save their crops from this pest. Given the potential losses from this pest, it is essential that the medfly not be allowed to become established in Florida.  Everyone can help fight this pest by cooperating with extermination efforts and following the do's and don'ts listed above. Good luck and good gardening.

Gene McAvoy is the horticulture agent with the Hendry County Extension Service.  Direct your horticulture questions to PO Box 68, LaBelle, FL 33975,  e-mail - or phone 863-674-4092 or 863-983-1598.  You are also welcome to visit the Hendry County Extension Office at 225 Pratt Blvd., LaBelle.   Office hours are from 8:00 - 5:00.

The Institute of Food and Agricultural Sciences is an Equal Employment Opportunity - Affirmative Action Employer authorized to provide research, educational information and other services only to individuals and institutions that function without regard to race, color, sex, age, handicap or national origin.

Home                    Index