Horse radical on the left, simplified from 馬. The original sense of 骚 was a horse stamping and twitching, restless from the fleas on its hide. The radical anchors 骚 alongside other horse verbs like 骑 (ride), 驰 (gallop), 骏 (steed).
Right side 蚤 (flea) gives the sound (zǎo → sāo, sibilant drift) and reinforces the meaning. A flea-bitten horse is twitchy and disturbed — the literal source-image. From there 骚 generalised to 'agitation, disturbance' and the modern slang 'flirty' or 'pungent'.
