formation of infection structure penetration peg formation The assembly by the symbiont of a peg-like structure for the purpose of penetration into its host organism, which penetrates through the host cuticle and epidermal cell wall. The host is defined as the larger of the organisms involved in a symbiotic interaction. symbiont penetration peg formation for entry into host initiation of symbiont penetration peg symbiont penetration peg initiation Note that this term should not be used to annotate gene products of the host. It should only be used to annotate those gene products from the symbiont involved in this process. biological_process formation of symbiont penetration peg for entry into host GO:0075057 GO:0075053