Topoff and Ellen Zimmerli also did experiments to prove that the "Polyergus" queen "tricks" the "Formica" colony by obtaining chemicals from the "Formica" queen in the process of killing her. In one test, the "Formica" queen was killed (by flash freezing then thawing) prior to "Polyergus" contact. Even though it was already dead, the "Polyergus" queen bit, stabbed, and licked the queen just as if it were alive: and the "Polyergus" was consequently accepted by the colony. Another test showed that if no "Formica" queen was present, then "Polyergus" had little chance of a successful takeover. Clearly, the "Formica" queen is providing some sort of chemical(s) to the "Polyergus" queen, however unintentionally. That takeover can occur even if the host queen is dead, but not if she is not present, proves that chemical absorption is important. The "Polyergus" queen needs only kill one host queen to be accepted. If the colony was polygynistic, the "Polyergus" queen can take her time finding the other queens. "Hour by hour, day by day, she methodically locates and kills every "Formica" queen, sometimes taking several weeks to clear out all remnants of opposition".