Tree pine ("Pinus" species) the bark exudes sticky resin which deters attackers whereas in rubber trees ("Hevea brasiliensis") it is a milky latex that oozes out. The quinine bark tree ("Cinchona officinalis") contains bitter substances to make the bark unpalatable. Large tree-like plants with lignified trunks in the Pteridophyta, Arecales, Cycadophyta and Poales such as the tree ferns, palms, cycads and bamboos have different structures and outer coverings. Although the bark functions as a protective barrier, it is itself attacked by boring insects such as beetles. These lay their eggs in crevices and the larvae chew their way through the cellulose
Bark beetle that do not feed on fungi, by having the fungi do the work of overcoming the plants' chemical defenses. The beetles carry the fungal spores in special structures, called mycangia, and infect the trees as they attack them. Like many other insects, Scolytinae emit pheromones to attract conspecifics which are thus drawn to trees already colonized by bark beetles. This can result in heavy infestations and eventually death of the tree. Many are also attracted to ethanol, one of the byproducts of microbial growth in dead woody tissues. Bark beetle A bark beetle is one of about 220 genera with