walnut husk maggot (Rhagoletis suavis) male at Chipera Prairie IA 653A0754 -
This delightful little fruit fly is called the walnut husk maggot because its larvae look like little white maggots if you open up the mushy rotting husk surrounding a black walnut. The definitive key to this fruit fly's ID is that the black wing banding pattern spells out the word "IF" in capital letters. You can see my thumb here for scale. Female walnut husk maggot flies slice open a fresh "green" black walnut husk with their sharp ovipositor and deposit a dozen or so eggs inside the husk. Upon hatching, the larvae, or maggots, eat on the black walnut husk hidden from our view but they do not penetrate the walnut shell and enter the nut proper. When the larvae are mature they crawl out of the walnut husk and then tunnel several inches underground where they will pupate and spend the winter. Remember that the black walnuts are all fallen to the ground by then. Adults like this male emerge in late summer as the black walnuts are ripening on the tree and getting ready to fall, so if you have a black walnut tree in your yard be looking for this colorful tiny fruit fly right now!
walnut husk maggot (Rhagoletis suavis) male at Chipera Prairie IA 653A0754 -
This delightful little fruit fly is called the walnut husk maggot because its larvae look like little white maggots if you open up the mushy rotting husk surrounding a black walnut. The definitive key to this fruit fly's ID is that the black wing banding pattern spells out the word "IF" in capital letters. You can see my thumb here for scale. Female walnut husk maggot flies slice open a fresh "green" black walnut husk with their sharp ovipositor and deposit a dozen or so eggs inside the husk. Upon hatching, the larvae, or maggots, eat on the black walnut husk hidden from our view but they do not penetrate the walnut shell and enter the nut proper. When the larvae are mature they crawl out of the walnut husk and then tunnel several inches underground where they will pupate and spend the winter. Remember that the black walnuts are all fallen to the ground by then. Adults like this male emerge in late summer as the black walnuts are ripening on the tree and getting ready to fall, so if you have a black walnut tree in your yard be looking for this colorful tiny fruit fly right now!