Wikijunior:Bugs/Fruit Fly

What does it look like?

An adult Fruit Fly

Fruit flies belong to the Order Diptera and the Family Tephritidae. There are about 4500 species. Most have distinctive markings on their wings, such as bands, patches, or zigzags. Scientists use these patterns to identify individual species.

Mediterranean fruit flies (Ceratitis capitata) are called Medflies. They are about the size of a common house fly. Their wings have orange and brown markings. There are dark and light patterns on the head. The abdomen is orange with light stripes and the legs are orange.

Caribbean fruit flies (Anastrepha suspense) are mostly orange with some black markings. The wings are long with yellow-brown to brown bands. They are also known as Greater Antilliean fruit flies, guava fruit flies, and Caribfles. They can be 2 times larger than a common house fly.

Papaya fruit flies (Toxotrypana curvicauda) have a long, thin body. There are orange patterns on the head and thorax, and orange and brown stripes on the abdomen. The transparent wings are long and thin and held straight back over the body.

Asian papaya fruit flies (Bactrocera papayae) are black with yellow patterns on the thorax. The wings are transparent.

Olive fruit flies (Bactrocera oleae) are black with transparent wings. They have a reddish pattern on the head and abdomen.

European fruit flies (Icterica westermanni) are also known as “picture wing” flies. They are brown with tan stripes and have whiteish spots on brown wings.

Where does it live?

Fruit flies occur worldwide and live in a wide variety of habitats.

Medflies are thought to have originated in Africa. They are now found in many other parts of the world.

Caribbean fruit flies are native to the West Indies. They are found in Cuba, Jamaica, Hispaniola, Puerto Rico, and South Florida.

Papaya fruit flies are found throughout tropical and subtropical areas of the western hemisphere. They are found in Central and South America. In the United States, they are found in southern Texas and southern Florida.

Asian papaya fruit flies are found in Thailand, Malaysia, Borneo, Indonesia and Singapore, Papua New Guinea, and in Australian island territories.

Olive Fruit flies probably came to the Middle East and southern Europe from Africa. Scientists believe they were recently introduced to California olive groves from the Mediterrean region.

What does it eat?

Caribbean fruit flies infest only mature to overripe fruits. They feed on peaches, plums, oranges, grapefruit, guavas, rose-apples, and cherries.

Papaya fruit flies eat papaya, mango, and milkweed.

Adult Olive fruit flies feed on various substances including honeydew from insects, pollen, and bird droppings.

European fruit flies feed on the flowerheads of ragwort.

How does it defend itself?

Scientists have found that some fruit fly species change colors and patterns within a few generations. To blend in with different surroundings, a new generation may become darker or lighter than previous generations. Scientists believe this adaptation makes the new generation of fruit flies less visible and protects them from predators.

What stages of metamorphosis does it go through?

Fruit flies undergo complete metamorphosis, changing to an adult in several stages: egg, early larva, full-sized larva, pupa and adult. While in the pupal stage, they “rest” before the final molt to full grown adult.

Eggs are laid on plants. Some larvae feed and grow inside soft fruits or flowers. Others are leaf-miners or gall-formers. Larvae vary in shape and are smooth or slightly spiny.

Adult Medfly females deposit their eggs in fruit skin that has been softened by damage. The eggs hatch within 3 days. Larvae grow inside the fruit. The flesh of the fruit decomposes as larvae feed. When fully grown, larvae stop feeding and leave the fruit. They burrow into the soil, pupate, and slowly develop into adults. Adults escape from the pupal case and burrow up through the soil. The amount of time from egg to adult varies from five weeks to five months, depending on temperature. Adults may live 2 to 3 months.

Caribbean fruit fly eggs are laid one at a time and hatch in 2 to 3 days. The larvae feed and grow for about 2 weeks. The pupal period is about the same. Development from egg to adult takes longer in cooler weather.

Female Papaya fruit flies produce hundreds of long, slender eggs. The eggs are deposited in immature papaya fruit. Young larvae feed on developing seeds in the center of the fruit. Unripe papaya juice is fatal to young fruit flies, so they wait for the fruit to become ripe. They eat their way out and drop to the ground. They mature beneath the plant, just under the surface of the soil. Adults emerge in 2 to 6 weeks.

Asian papaya fruit flies lay their eggs along with fruit-decaying bacteria just under the skin of the fruit. The inside of the fruit is damaged before signs of infestation appear on the outside. Small discolored patches appear where the female punctures the skin to lay eggs. Within 1 to 2 days, eggs hatch into larvae which feed on the decaying fruit. After the decayed fruit drops to the ground, it takes 7 to 12 days for the larvae to leave the fruit and burrow into the soil to pupate. Mature adults emerge about 2 weeks later. In 1 to 2 more weeks mating begins. They live for several months and reproduce throughout their life span. They are able to multiply rapidly and disperse over great distances.

Olive fruit flies only reproduce on olive fruit. Females prefer large green olives for egg-laying. Eggs are laid under the skin of the fruit. A few days later, the larvae appear. They feed on the pulp and pass through 3 larval instars. Pupae develop inside the fruit or on the ground.

What special behavior does it exhibit?

Male Medflies sing a unique “calling song” when courting females. A female will mate with a male whose sound tones are most attractive to her.

How does this bug affect people?

Many fruit fly species cause extensive damage to crops and fruit trees. Countries and states make rules against importing fruit from areas where fruit fly infestation has occurred.

Medflies damage citrus and other soft fruits. They multiply rapidly. People place Medfly traps on trees. If just one is found in a trap, citrus farmers prepare for the worst.

Asian papaya fruit flies are a serious quarantine pest worldwide. They infest virtually all fruit, except pineapples, legumes, sweet corn, macadamia nuts, and coconuts.

Olive fruit flies have been the major pest of olive crops worldwide since biblical times.

Reference

Deyrup, M. (2000). Florida’s fabulous insects. Tampa, FL: World Publications.

McGavin, G. C. (2000). Insects spiders and other terrestrial arthropods. New York, NY: Dorling Kindersley, Inc.

http://agspsrv34.agric.wa.gov.au/Ento/medfly.htm

http://www.ars.usda.gov/sp2UserFiles/person/3559/publications/2003-asae-medfly-final.pdf

http://www.ars.usda.gov/is/AR/archive/feb09/olive0209.htm?pf=1

http://cisr.ucr.edu/olive_fruit_fly.html

http://www.dpi.qld.gov.au/4790_6952.htm

http://entomology.ifas.ufl.edu/creatures/fruit/tropical/caribbean_fruit_fly.htm

http://www.hhmi.org/news/carroll20091217.html

http://www.westpakavocado.com/multimedia/Quarantine/MedFlyFactSheet.pdf

http://en.wikipedia.org/wiki/Ceratitis_capitata