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Insect Hair

Insect Hair

These two hairs show the characteristic attachment structure, the central cavity, the birefringence, and some of the variability in structure common in most insect hairs. The upper hair is plumose (feathery) and the lower hair is smooth. This image is from a tapelift of house dust.

Transmitted Off Crossed Polarized Light Illumination


Insect "hair" is not like mammalian hair. It is refered to as hair because of its similar appearance on the insects body. Techincally they are more properly called seta (pl. setae). Chemically it is Chitin rather than Keratin. Keratin is a protein that contains sulfur and will react with sodium azide solution while chitin is a nitrogen containing polysaccharide.

Significance in the Environment:

Some individuals are alergic to insect debris, including body fragments and hair. Some hairs are stiff enough to be an irritant of mucosal tissue and the skin. Some insect fragments and hair contain compounds that are chemical active in the human body.

Characteristic Features:

The setae and the rest of the exoskeleton are basically the nitrogen containing polysaccharide chitin. Chitin is oriented in such a way that the exoskeleton fragments show little birefringence. The setae on the other hand may be quite birefringent. The birefringence in the setae is highly variable and becomes a distinguishing feature, in some cases identifying species and in others identifying genera. The birefringence of insect setae is never as high as in the cellulose plant hairs or some of the chitin setae of mites, but it is higher than in the exoskeleton fragments.

Associated Particles: