It is used in locomotion
The cockroaches possesses smooth flexible pads found at the distal end of the leg on tarsus. The fifth segment is the most flexible, found at the distal end and is made of a broadly triangular adhesive pad called as the arolium. The arolium is the adhesive organ of the cockroach foot engaged when the legs are pulling and used in scaling and adhering to the smooth surfaces. So, arolium helps in locomotion
So think of arolium as cockroach organ lube
