Start your control of the Mealy Bugs with a good sharp water spray to knock off as many as possible and follow that up with some insecticidal soap sprays. Overwatering is the single most common problem with house plants so cut back and water only when the plant really needs it.

Be aware that insecticidal soap may damage succulent plants. You'd be wise to test it on a small portion of the jadeplant (perhaps one branch), then wait a week to see the result.

Oooh, jean001 is so right! Jade is one of the plants that may suffer damage from insecticidal soap applications. But I will tell you what you can use, with great effectiveness! Mix a solution of one part rubbing alcohol to three parts water (or stronger) and fill a small spray bottle. Apply liberally to all parts of the plant, even after you see no obvious signs of mealy bugs.