Engorged blacklegged tick larvae

Tick eggs hatch into larvae that have 3 pairs of legs (unlike the nymphs and adults that have 4 pairs). Larvae feed once on a host such as a mouse, usually in late summer, at which point they are refered to as "engorged".

These engorged larvae, full of mouse blood, may molt in nymphs within a few weeks, or later in the year may choose to overwinter and not emerge until the following Spring.