MEXICAN FRUIT FLY (MFF): Anastrepha ludens (Loew) Order - Diptera: Family - Tephritidae

DISTRIBUTION: MFF occur in Mexico, Central America and northern South America. There is normally an annual migration into the Rio Grande Valley of southern TX. There are numerous introductions into southern CA.

DESCRIPTION: The egg (Fig 2) is a minute cylinder strongly tapered at one end. The legless larva (Fig 3) is a white maggot, pointed at one end where the black mouth hooks are visible. The mature larva is 9-11 mm. in length and 1.5 mm. in diameter. The pupae (Fig 4, typical fruit fly pupae) is tan to dark brownish-yellow.

The adult fly is beautifully colored with yellowish-brown body and green eyes. It has 2-3 whitish stripes along the thorax. MFF is slightly larger than a housefly [7-10 mm. (.38”) in length]. The wings are clear except for several yellow and brown stripes. The inverted V on the lower part of the wing is broken at its tip and is usually not connected with the main pattern. The ovipositor sheath of the adult ♀ is longer than the remainder of the abdomen. The ♂ lacks an ovipositor (Fig 6, to right of center).

HOSTS: While many tropical and subtropical fruits are known as hosts, some of the favorites are Citrus spp. (grapefruit is prime), sapote, mango, peach and avocado. The ♀ typically oviposits at the time the fruit begins to show color.

DAMAGE: Feeding larvae reduces interior of fruit to a rotten mass. Egg punctures admit decay organisms.

INSPECTION TIPS: Cut and inspect prematurely dropped fruit and fruit with softened, darkened, broken down areas, distorted in appearance. Look for egg punctures that may be surrounded by liquid droplets or ringed by small craters. Exit holes are conspicuous, usually appearing after the fruit has dropped. Traps filled with water bated with yeast can be used to detect MFF.

LIFE CYCLE: Eggs are laid singly or in groups of up to 18, and a female may lay several thousand eggs in her lifetime. Larvae go through three instars and may require from 11 days to over a month to complete development depending on temperature. At maturity, the larvae exit the fruit and burrow into the soil to pupate. Adults emerge from 12 to 100 days later depending on temperature. Newly emerged adults usually require from eight to 34 days to mature prior to egg laying. Breeding is continuous with four to six generations a year under optimum conditions. Complete cycles have been recorded as short as 36 days.

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