Some Manila copal was obtained by probing the ground below Agathis trees with long rods. It was obtained mainly, however, by tapping the tree, usually the bole though in Sabah and New Zealand, cuts were also made on the limbs so that huge, pendulous masses of resin developed. Average annual yields of 10-12 kg/tree can be obtained. Yield increases during the first six months of tapping and, as is the case with pines, resin flow can be stimulated with the application of sulphuric acid