Lac, known as shellac in its refined form is a secretion from an insect. Lac has been known in India since ancient times.

Phenology and Silviculture

Lac is a resinous substance secreted by tiny lac insect, Laccifer Lacca Kerr, as a protective covering. The insect is found as a parasite on number of plants, both wild and cultivated. Out of hundred species of plants that act as hosts for lac insect in MP, 3 species of Palas (Butea Monosperma), Ber (Zizyphus Mauritianaa) and Kusum (Schleichera Oleosa) together account for 85 percent of production.

For commercial production of Lac, the larvae are introduced to their new host through a process of infection or inoculation; branches bearing mature lac, from which larvae are about to emerge, are tied to new host. These 'brood' sticks contain enormous numbers of larvae, which crawl on to young branches of host tree, and begin to feed by forcing their mouthparts through the bark on sap of the host tree. The larvae settle in close proximity to each other forming virtually a continuous layer.

Once the layers are settled they begin to secrete lac that forms as a shell over their bodies. The lac larvae grow inside the coating and continue to secrete lac, which coalesces into a continuous encrustation. The lac larvae undergo several morphological changes within this encrustation. Upon reaching sexual maturity the adult males fertilize the females and shortly die thereafter. The females continue to secrete lac while fertilised eggs continue to develop. The eggs once mature are deposited in an incubating chamber where they hatch into larvae. The new generation of larvae emerge (swarming) and establish themselves on new shoots, thus beginning a new cycle.

Utilisation

Lac that was used in Asia and India for impressing seals, in the modern times found its use in plastics, electrical goods, as adhesives, leather, wood finish, printing, polish and varnish, ink and a number of other industries. It is also principal ingredient of sealing wax.

With arrival of synthetic resin, demand for lac went down. However, Lac has found a new use in the recent years i.e. in the computer chips as it is a good insulator. It is expected that there will be high demand for the produce in the near future.

Collection and Processing

Lac is harvested by cutting the resin-encrusted twigs off of the tree. This is usually done by trimming the twigs that are within hands-reach, or by climbing the tree to get at the lac infested branches. A few lac-encrusted twigs are left for facilitating re-infection of the tree. The practice of cutting twigs does not overly damage the tree, and in fact provides relief to the tree from continuous drain on its resources by the insect. The cutting of twigs is similar to pruning and allows for growth of fresh flush of branches. These few branches provide lac insect with healthy sites for colonisation during next swarming.

Production and Pricing