<P> Trichomes are an essential part of nest building for the European wool carder bee (Anthidium manicatum). This bee species incorporates trichomes into their nests by scraping them off of plants and using them as a lining for their nest cavities . </P> <P> Plants may use trichomes in order to deter herbivore attacks via physical and / or chemical means, e.g. in specialized, stinging hairs of Urtica (Nettle) species that deliver inflammatory chemicals such as histamine . Studies on trichomes have been focused towards crop protection, which is the result of deterring herbivores (Brookes et al. 2016). However, some organisms have developed mechanisms to resist the effects of trichomes . The larvae of Heliconius charithonia, for example, are able to physically free themselves from trichomes, are able to bite off trichomes, and are able to form silk blankets in order to navigate the leaves better . </P> <P> Stinging trichomes vary in their morphology and distribution between species, however similar effects on large herbivores implies they serve similar functions . In areas susceptible to herbivory, higher densities of stinging trichomes were observed . In Urtica, the stinging trichomes induce a painful sensation lasting for hours upon human contact . This sensation has been attributed as a defense mechanism against large animals and small invertebrates, and plays a role in defense supplementation via secretion of metabolites . Studies suggest that this sensation involves a rapid release of toxin (such as histamine) upon contact and penetration via the globular tips of said trichomes . </P>

Density of plant hairs as a function of herbivory
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