Ptinidae (spider beetles)
Life > Eukaryotes > Opisthokonta > Metazoa (animals) > Bilateria > Ecdysozoa > Panarthropoda > Tritocerebra > Arthopoda > Mandibulata > Atelocerata > Panhexapoda > Hexapoda
(insects) > Dicondyla > Pterygota > Metapterygota > Neoptera > Eumetabola >
Holometabola > Coleoptera
> Polyphaga > Superfamily: Bostrychoidea
Small (2-5mm), spider-like beetles with
rounded, globular bodies and long legs. The head is obscured from above by the
pronotum. They are scavengers and feed on dry animal and vegetable matter and
are found in birds' , animal nests and caves.
Mezium americanum, American
[image H. Robertson, Iziko ©].
The American spider beetle is found
throughout the world and is a pest of stored products such as grains and cayenne
pepper. The smooth shiny elytra, the dense mat of hairs on the pronotum as well
as the interrupted (scalloped) line of dense hairs at the base of the elytra
make it easy to identify. There is a closely related stored product pest called
the Northern spider beetle Mezium affine but it is evidently only found
in the Northern Hemisphere. It is similar in appearance to M. americanum
but is distinguished from it in having a continuous line of dense hairs at the
base of the elytra (not scalloped).
If you encounter large numbers of these beetles in your
home it probably means there is an old bag of dried food in a cupboard somewhere
in which this beetle is breeding. Clearing out the infested food will solve the
problem although you need to watch out in case the beetles have started laying
their eggs in other exposed food nearby. Sealing of dried foods in plastic
containers would have prevented the problem in the first place.