Bombardment of any structure by a salvo of B gliders takes on the character of an erosion of the alpha lattice. Therefore it can be expected that it will eventually become periodic. Here the target can be D1 hi, which itself belongs to a cycle of eight, or D2 hi, which evolves into the D1 hi cycle after a transient, also of length eight.
Three of the nBhiD1 collisions, for . The gradual growth of the period 8 margin of the region of B gliders can be seen. Every time the T1 cluster to the left of the T4 launches a new glider to the left, the B tally for the reaction must be incremented; otherwise the whole process is cyclic. Note that the A glider which transforms D1 into D2 is implicit in all three diagrams, which could be made more evident by changing the coloring of some of the T3's.