Lewis Short
(verb) : in-serpo, psi, ptum, 3
* To crcep on or over any thing; only trop.; constr. with dat. (poet. and post-class.): jam somnus avaris Inserpit curis,Stat. Th. 1, 340: ei lanugo malis inserpebat,covered over his cheeks,App. M. 7, p. 189 fin.
Charlton T. Lewis, Charles Short, A Latin Dictionary