what is the latter ?
It is also known as the railroad worm, is a species of fruit fly, and a pest of several types of fruits, mainly apples
Apple maggot
The apple maggot ("Rhagoletis pomonella"), also known as the railroad worm (but distinct from the "Phrixothrix" beetle larva, also called railroad worm), is a species of fruit fly, and a pest of several types of fruits, mainly apples. 
where do apples grow in the united states North America what are apples ? An edible fruit produced by an apple tree name its wild ancestors ? "Malus sieversii" is it used in any form of art ? UNANSWERABLE is it referred in greek mythology ? Yes, according to Greek mythology  to throw an apple at someone was to symbolically declare one's love; and similarly, to catch it was to symbolically show one's acceptance of that love name its popular uses ? Important ingredient in many desserts, such as apple pie, apple crumble, apple crisp and apple cake, also apples are milled or pressed to produce apple juice, etc. how is it used in research ? Preliminary research is investigating whether apple consumption may affect the risk of some types of cancer name some pest which effect this fruit ? Codling moths and apple maggots
wiki:389302
Apple maggot [SEP] Introduction
The apple maggot ("Rhagoletis pomonella"), also known as the railroad worm (but distinct from the "Phrixothrix" beetle larva, also called railroad worm), is a species of fruit fly, and a pest of several types of fruits, mainly apples. This species evolved about 150 years ago through a sympatric shift from the native host hawthorn to the domesticated apple species "Malus domestica" in the northeastern United States. This fly is believed to have been accidentally spread to the western United States from the endemic eastern United States region through contaminated apples at multiple points throughout the 20th century. The apple maggot uses Batesian mimicry as a method of defense, with coloration resembling that of the forelegs and pedipalps of a jumping spider (family Salticidae).