To deter intruders such as insects, fungi and bacteria, the larch closes its wounds with resin.
Strong bending caused by avalanches or wind can cause small cavities under the bark. These occur when the soft, active layer of divisible cells (cambium) is loosened from the wood cells by bending. Cavities then fill with resin to protect the tree against insect infestation.
In a healthy larch, resin is transported through channels called resin ducts. These resin ducts are formed by specialized cells - called epithelial cells - which release resin into the duct.
Resin has an antiseptic effect against fungi and bacterial diseases.