Historical clue formulations

• They "hatch" late in life — 2023-05-12
• They're saved for a rainy day — 2022-04-22
• Some caches — 2016-03-17
• Some reserves — 2010-07-10
• Pension supplements — 2007-03-09
• Seniors may use them — 1999-09-18
• Savings kitties: 2 wds. — 1999-05-16
• Rainy day reserves — 1998-12-30
• Cash reserves — 1994-02-21