Insect Hairs
These two hairs show the characteristic attachment
structure, the central cavity, 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
Definition/Function:
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:
References:
