The ultrastructure of the trachea of the compound eye in adult cabbage butterfly, Pieris rapae L., was studied. Trachea under the basement membrane is divided into tracheoles of the ommatidia which blanched 4 tracheoles during 2 divisions. Tracheoles of the ommatidia originated from one tracheolar cell and its nuclear is located under the basement membrane and its cytoplasm enveloped the retinular cell and the retinular pigment cell. The modified structure of tracheoles is located at the first division area of the ommatidia and its size is $8{mu}mX4.5{mu}m$. And the length of its taenidium is $0.1{sim}0.6{mu}m$, diameter $0.15{mu}m$, and interval $0.3{mu}m$.