Pick up a cheap automotive stethoscope. I don't know about this particular weevil, but the larval phase Giant Palm Weevil (Rhynchophorus cruentatus), which we get in Florida, makes enough noise clicking its mandibles as it chews its way through the palm, that you can hear it with a stethoscope.
Unfortunately, with a sneak attack like this, against a plant that has only an apical meristem, it's next to impossible to detect the bugs in time to save the plant. Most times you just wind up treating the dying tree in an effort to halt the spread.
Safari, applied as a bud/trunk drench, will halo the little rascals, if applied in time. If the palms are expensive, it can be worthwhile for property owners to budget for an annual treatment on a prophylactic basis vs the potential cost of take-down and replacement.
