Urticating Hairs in Arthropods: Their Nature and Medical Significance

Abstract

The ecological phenomenon of arthropods with defensive hairs is widespread. These urticating hairs can be divided into three categories: true setae, which are detachable hairs in Lepidoptera and in New World tarantula spiders; modified setae, which are stiff hairs in lepidopteran larvae; and spines, which are complex and secretion-filled structures in lepidopteran larvae. This review focuses on the true setae because their high density on a large number of common arthropod species has great implications for human and animal health. Morphology and function, interactions with human tissues, epidemiology, and medical impact, including inflammation and allergy in relation to true setae, are addressed. Because data from epidemiological and other clinical studies are ambiguous with regard to frequencies of setae-caused allergic reactions, other mechanisms for setae-mediated disease are suggested. Finally, we briefly discuss current evidence for the adaptive and ecological significance of true setae.

It's Not a Bug, It's a Feature: Functional Materials in Insects

“…Anatomical allomone structures Bees, [486,491] wasps, [486] ants, [486] honeybees, [497] true bugs [473,499,607] Defense spines Lepidopteran caterpillars, [485] pine processionary caterpillars, [485,490] moths [486] Built structures Caterpillars, [608][609][610][611] moth caterpillars, [612] beetles [613][614][615] Projectile dispersal Bombardier beetles [467] Color vision and color manipulation 1D photonic structures Beetles, [289,291] butterflies [289,291] Apposition eyes Ants, [361] dragonflies [361] Bioluminescence Fireflies [616] Color vision Honeybees, [617,618] common bluebottle butterflies [619] Disorder-based color Butterflies, [320,323,324] jeweled beetles, [329][330][331] white beetles [332,333] Photonic crystals Weevils, [290,316,319,321] butterflies [290,316,…”

“…Urticating structures have been reviewed extensively; [485][486][487] the three most prevalent defensive apparatuses in caterpillars are true setae, modified setae, and spines (Figure 21). True and modified setae are barbed hairs that grow from a modified cell at the base of the hair, while spines are more complex projections of the epidermis containing a number of specialized cells; all these structures are chitinous and hollow, but they vary widely in size.…”

“…Functionally speaking, spines and modified setae are similar in that both have sturdy bases and sharp tips, both can contain venom provided by specialized secretory cells, and both primarily function by sticking into attackers tip-first. [485] Caterpillars can pressurize the lumen of the secretory apparatus to inject considerable volumes of poison; [486] the tips of spines and hairs also often detach easily into the skin of the attacker. [488,489] True setae have a fundamentally different mechanism of action.…”

Public at Risk—Public as Risk: Regulating Nature by Managing People

“…Larvae of the moth release nettling hairs that can cause severe allergic reactions in people (Battisti et al 2011). In 2004 an outbreak occurred in a 4000-ha area of southern Gotland.…”

The oak processionary moth: a new health hazard?

“…The larvae of these caterpillars are equipped with fine, barbed hairs (setae, 0.2 mm), which can readily penetrate the human skin. 5,6 One of the major issues with the hairs is that they readily detach and can then be blown via wind currents for considerable distances. The older larvae (fifth and sixth instars) are of particular concern as they can carry up to half a million of the urticating setae per caterpillar.…”