Rhagoletis juglandis, also known as the walnut husk fly, is a species of tephritid or fruit fly in the family
The adult form of this fly is around 4 mm long. R. juglandis are distributed in Arizona, California, Texas, Kansas, and Mexico. The species infests the fruits of several species of walnut trees including
The larvae are small and infest walnut fruits, having hatched from eggs laid by adult females under the surface of the husk of the walnut. The insect overwinters as a pupa in the soil, and adults emerge in mid to late summer. R. juglandis engages in
Although courtship behavior is rare in the Rhagoletis genus, male flies demonstrate low-frequency wing vibration, accompanied by airborne infrasound; they also turn their wing edges upward. R. juglandis participate in a resource-defense mating system. Females follow resource-based cues such as ripeness (color), whereas males follow females for more opportunities to mate. The flies also respond to sex ratio to alter the amount of time that copulation takes. When male density is high, copulation times are longer.
R. juglandis was first described by E.T. Cresson, Jr. in 1920 from material from the