Western Cherry Fruit Flies

Facts, Identification & Control

SCIENTIFIC NAME

Rhagoletis indifferens

APPEARANCE

Adult western cherry fruit flies are black with white bands on their abdomens. The wings are clear and have a characteristic dark pattern, a feature that is used to distinguish WCFFs from other fruit flies. The adult is about 1/5 inch long, and the female is slightly larger than the male. The WCFFs undergo complete metamorphosis – an egg, larva, pupa and adult stage.

BEHAVIOR, DIET & HABIT

WCFFs prefer domestic and wild cherry trees as their hosts. Female WCFFs normally lay about 50-200 eggs during an egg laying period. That typically lasts about three weeks. The eggs hatch about 5 to 8 days after being deposited under the cherry fruit’s skin. The larvae – the fruit damaging stage – burrow inward until reaching the pit. Larvae have tube-like breathing systems and retractable mouthparts that assist them in feeding, tunneling, and living inside of fruit. After reaching full maturity, the larvae then bore out of the fruit and drop to the ground. Several hours after falling to the ground, larvae burrow into soil to pupate and overwinter. The adults emerge in May-August. Adults are weak fliers and will fly no further than what is required to find a host cherry tree.

REPRODUCTION

Reproduction by WCCFs is typical of insects that develop by complete metamorphosis and typically produce only one generation per year. Some birds and rodents are predators that impact population numbers, but they also consume the fruit and are not considered beneficial by fruit growers.

SIGNS OF A WESTERN CHERRY FRUIT FLY INFESTATION

While a sign of infestation may be the appearance of adult flies, more likely the evidence of an infestation is the appearance of larvae damage to the fruit and appearance of birds preying upon the larval-infested fruit.

DISTRIBUTION

The western cherry fruit fly is found throughout regions of the western United States that grow cherries.

MORE INFORMATION

Commercial cherry growers suffer revenue loss when their cherry fruit is infested and not acceptable for marketing, but many homeowners who have cherry trees are also affected. Homeowners that experience fruit damage by WCFFs can use some practical, non-chemical, preventive strategies that may include the following:

  • Using ground barriers such as dense mulches and landscape fabrics placed around the base of trees to prevent larvae from burrowing into the soil, thus reducing pupation and adult fly emergence.
  • Removing all cherries from the tree after harvest. This is a strategy that will eliminate any larval-infested fruits that were left on the tree.
  • Removing any cherries that have dropped to the ground and may contain larvae.
  • Consulting with their local extension service or knowledgeable nursery grower before planting to determine what cherry tree varieties are best for their situation.
  • Maintaining the overall height of their cherry trees so they are no taller than the homeowner’s ability to reach all of the fruit when harvesting.

If the above non-chemical methods are not sufficient, contact your pest management professional who can provide advice and assistance when needing to use chemical or biological products to control WCFFs and their damage.