Survival’s upper echelon includes the category “caregiver.”

Savvy creatures.

They often start small, but — like the lowly caterpillar that grows and spreads its butterfly wings — they can osmose into a form that flits, grows and takes over.

Dr. Ruth just had a minor stroke. The hospital’s running tests.

Affected was the left side of her brain which controls the right side, like the arm’s movement.

Medics seem confident with therapy treatment, which starts soon.

She’ll regain most strength. She hasn’t her hearing aids, so don’t call.

Awake, she is alert but does not know how to text.

A caregiver’s first rung is lower level — driver, butler, valet, housekeeper, maid, nurse, assistant. We speak big-time. Employers often have big wallets.

Billionaire heiress Doris Duke — Duke University, Duke tobacco — passed away at 80. Homes everywhere — Hawaii, Newport, Beverly Hills, New York. Companion? A butler who trickled into a confidante, keeper of the flame, the phone, the friends — the caregiver.

Bernard Lafferty, Irish, 51. Out of rehab. Broke.

To prevent break-ins, locks were on every window. Chains rumbled over each at night — same way jewelers protect their frontage. 

Bob Balaban produced HBO’s 2006 film “Bernard and Doris,” starring Susan Sarandon and Ralph Fiennes. Its party was in my home.

Why? I own Doris’ apartment. After her death I bought it.

That the late Bernard did her in wasn’t proven. That her estate left him millions was proven.

Caregivers come in all shapes and services. Babysitters, nannies, drivers, cooks, Alzheimer’s companions, housekeepers, second cousins.

Celebrities have had those lawsuits.

When a haul-my-trash-to-the- dumpster gopher rises to chief of staff they’ve heard, seen and know everything. Even how often you hit the john. They take over.

One VIP handed a sofa blanket to a visitor who’d not requested it. Not having first been consulted, the caregiver told the recipient: “You don’t need this.” Peeled it right off the visitor’s arm at the door and took it back.

A helper was given a thank you sweater. The caregiver later removed it with: “You can’t have this. It’s too expensive.”

So what is it? Jealousy? Need to show importance?

One housekeeper almost kept the whole house. Wore shorts in summer. Sat in the dining room with guests. Involved herself in family decisions.

Even during private chats some stay plunked front and center.

Their answer could be: “Just trying to help with whatever might be needed.” Real answer? No one may hear, know, see or smell what’s behind closed doors.

Once, a forever friend was handed a gold bracelet. The “Chief of Staff” interjected: “You have no right to that. She never checked that with me. It wasn’t even on my list.”

Caregivers are not always family. And our population is growing older. Needier. Long years ago, when my household was in need, things disappeared.

Like cash.

I’m just letting you know.