31 August 2024
After yesterday night’s rainbow a “triangle fly” landed on our eating room window and spun its physique slowly like a high. Google Lens recognized it as genus Rhagoletis, a member of the fruit fly household Tephritidae.
There are about 25 species of Rhagoletis native to North America, every with its personal host fruit. Those that eat the fruits we develop commercially, comparable to cherries and walnuts, are thought of agricultural pests.
Since my picture reveals the bug’s underside, Google Lens picked up on the yellow physique and recognized it because the walnut husk fly, Rhagoletis completa, although it could have been a special species such because the carefully associated Rhagoletis suavis. There are black walnuts in Pittsburgh’s parks so these species are potentialities.
Right here’s a topside view of Rhagoletis completa.
Grownup feminine Rhagoletis inject their eggs into the host fruit in order that the larvae have one thing to eat once they hatch. For those who open an infested fruit it seems to be prefer it has maggots. Right here’s a walnut husk (sure, it’s a fruit) with R. completa larvae in it.
Maybe that’s why we sometimes see rotting black walnut husks on the bottom.
Rhagoletis are preyed upon by leaping spiders!
Some species mimic leaping spiders. The wing-waving apparently deters the strategy of leaping spiders, vital predators of the flies. Different species have brightly-patterned our bodies, and should mimic wasps.(3)
“Spider predation has been intense sufficient to mould the evolution of prey traits: predation by salticids (leaping spiders) has formed the morphology and conduct of some tephritid flies. Their wing markings resemble the sample of the legs of leaping spiders; the flies additionally wave their wings in a vogue that seems to imitate the agonistic conduct of salticids – making them ‘proverbial sheep in wolf’s clothes’.”(8)
May this native North American leaping spider be a predator of our Rhagoletis flies? Do you see a resemblance between its angled legs and the sample on the fly’s wings?
The triangle fly has opened an entire new space of inquiry.
