Mezium affine (Boieldieu, 1856)

Nom usuel
Ptine luisant
Nom usuel
Hood Spider beetle
shiny Spider beetle
shining Ptinus
Nom usuel
Escarabo araña
Nom usuel
Ordre   Coleoptera
Famille   Anobiidae
Genre   Mezium
Espèce   affine


Ptinidae were once a family of their own, but they have now been included into the Anobiidae family (cf. fact-sheets).
Shiny spider beetles have a characteristic aspect and can be mistaken for small spiders, hence their name.
They are polyphagous insects that feed on dry organic debris of animal or plant origin.
They are common inconspicuous guests in museums, warehouses, housings, libraries, cellars, attics… where they can cause some damage to various materials and products. 

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Critères de reconnaissance


2.5 to 3.5 mm long

Look like small spiders, but have only 3 pairs of legs (spiders have 4).
Sturdy, rounded, pearl-shaped body. Upper part of abdomen completely smooth. Fairly long, 11-articled antennae.


Shiny, fully orange-brown elytra. Head, thorax and legs entirely covered in a dense, scaly, golden or greyish pubescence.


4.5 mm long at the last developmental stages.

Look like small, slightly arched white grubs, with a more or less erect hairiness


Yellowish white body, brownish yellow head. Yellowish hairiness.

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Cycle de développement

The biology of that species is close to that of other Anobiidae species.
Their development cycle requires 12 to 16 weeks on an average, but only 7 in optimal conditions at 33°C.
They are a univoltine species (there is only one generation per year) whose growth rate is low despite a rather short time span needed to reach full development.
Females’ fecundity varies between 50 and 100 eggs. They are laid in early summer and hatch 2 weeks later. Larval development requires 6 weeks on an average. Nymphosis takes place in a kind of tight cocoon, and after 3 or 4 weeks adults get out and reach the outside world.

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Matériaux infestés

Liste des matériaux infestés par cet insecte :
Spices, plants
Spices, plants, Chitin, Collagen, Keratin, Starch

Mezium affine have a polyphagous food diet composed of grains, all kinds of seeds, dried fruit, dried meat, wool, hair, hairs, feathers, skins, book-bindings, insect remains, dried mushrooms, animal excrements, sugar, and many more foodstuffs. They are fond of dark, quiet places (cellars, barns, attics) and are preferentially found in old food stores, libraries, museums, where they can infest animal collections, amongst others. 

Aspect des dégâts

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They are widely distributed worldwide, except in Asia.

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Espèce(s) apparentée(s)

Indice de fréquence : 2 / 5

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Autres informations

Site mis à jour le vendredi 13 mai 2016, à 11:45

Responsable de publication : Roland May