The situation under investigation is a combination of two pests and I don't think it has been described yet (see reference below).
The rhinoceros beetle can defoliate palms of any age or height, rarely killing adult palms but extremely dangerous to seedlings and young palms.
What is killing adult palms of any height is coconut lethal yellowing disease and it can wipe out an entire plantation in 4 years, leaving only the topless stems.
These have to be removed otherwise the beetle larvae have an almost unlimited food supply and when the adults emerge they attack seedling coconuts, planted to replace those destroyed by lethal yellowing.
I want to know if the larvae are edible because that would encourage farmers to "harvest" them - thereby eliminating danger from the adult beetle and perhaps generating an income until the seedling coconuts come into bearing.
Hugh
The following is from Mariau, D. (1999) The Insect Pests of Coconut In: J.G. Ohler (ed) Modern Coconut Management, Part 1, Chapter 7, pp 103-116
<http://ecoport.org/ep?SearchType=earticleView&earticleId=127&page=1307>.
"From the axil of a young leaf, the adult bores a tunnel through the spear. When opened, the affected leaves show a V-formed cut. In severe and repeated attacks (the tunnels may reach a length of 1 metre), defoliation may be serious, even in adult palms. The palms are rarely killed, except under conditions that are particularly favourable to the insect. In young palms, however, this is not the case, as the tunnels often reach the tissues near the meristem of the growing point, causing serious deformations of the stem and, if the meristem has been affected, resulting in the death of the palm.
The larvae live in decomposed wood and in compost, where they complete their development through three stages. Their cycle covers about 3 months. The larvae are curved and are white-greyish, with a head equipped with powerful, hardened jaws. The pupal stage, which takes about 20 days, is passed in a hole cut in the wood, or within a fibrous cover."