''Thylodrias'' is a
monotypic genus
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...
[''Thylodrias contractus'' (Motschulsky, 1839).]
Pest Insects of our Cultural Heritage. Centre Interdisciplinaire de Conservation et de Restauration du Patrimoine. of
beetle
Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...
s in the family
Dermestidae
Dermestidae are a family of Coleoptera that are commonly referred to as skin beetles or carpet beetles. Other common names include larder beetles, hide or leather beetles, and khapra beetles. There are over 1,800 species described.
Dermestids ha ...
containing the single species ''Thylodrias contractus'', known commonly as the odd beetle and tissue paper beetle. It is native to Asia and is a widespread
introduced species
An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived ther ...
in North America.
[Ebeling, W]
Chapter 8: Pests of Fabrics and Paper.
''Urban Entomology''. University of California, Riverside. 2003. It can be a
pest at times.
Description
''T. contractus'' is an elongate beetle with slender legs. The male can be recognized by its yellowish-brown
elytra
An elytron (; ; : elytra, ) is a modified, hardened forewing of beetles (Coleoptera), though a few of the true bugs (Hemiptera) such as the family Schizopteridae are extremely similar; in true bugs, the forewings are called hemelytra (sometime ...
and covering of silky, white hairs. The abdomen has seven sternal segments and the antennae are filamentous rather than club-shaped, which distinguishes it from all other members of the Dermestidae.
[Arnett, R., et al. ''American Beetles''. CRC Press, New York, NY. 2002.][Dillon, E. and L. Dillon. ''A Manual of Common Beetles of Eastern North America''. Row, Peterson and Company, Elmsford, New York. 1961.] The female looks very different from the male. It resembles a
larva
A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...
, and though it is free-living and has legs and antennae, it lacks elytra and hind wings.
The larva of the odd beetle resembles that of most other Dermestidae, but it lacks a tuft of hair at the posterior end and any long hairs along the dorsal surface. At the end of each segment of the body is a row of short bristles.
Natural history
Life cycle
Like all beetles, the odd beetle undergoes
complete metamorphosis
Holometabolism, also called complete metamorphosis, is a form of insect development which includes four life stages: egg, larva, pupa, and imago (or adult). Holometabolism is a synapomorphic trait of all insects in the clade Holometabola. Immature ...
, or a dramatic reorganization of the body plan of the insect and the formation of two distinct life stages, growth and reproduction, which are separated by a pupal phase. Although the female is larviform, she also undergoes metamorphosis from a true larva to a sexually mature adult. Once ''T. contractus'' has reached sexual maturity, the female produces a
sex pheromone
Sex pheromones are pheromones released by an organism to attract an individual of the same species, encourage them to mate with them, or perform some other function closely related with sexual reproduction.
Sex pheromones specifically focus on ind ...
which attracts the male.
[Mertins, J. (1982)]
Sex pheromone communication in the odd beetle, ''Thylodrias contractus'' Motschulsky.
''Journal of Chemical Ecology'' 8, 653-61. Once the female has mated she no longer produces this pheromone, which suggests that she mates only once. There is no indication that this is true for the male.
[
]
Behavior
The odd beetle was given its other common name, the tissue paper beetle, because it was believed to eat tissue paper
Tissue paper, or simply tissue, is a lightweight paper or light crêpe paper. Tissue can be made from recycled pulp (paper), paper pulp on a paper machine.
Tissue paper is very versatile, and different kinds are made to best serve these purposes ...
.[Berenbaum, M. R. ''Ninety-nine More Maggots, Mites, and Munchers''. University of Illinois Press, Chicago, IL. 1993.]
The beetle is usually found in dark corners of human structures, such as drawers, cupboards, and museum
A museum is an institution dedicated to displaying or Preservation (library and archive), preserving culturally or scientifically significant objects. Many museums have exhibitions of these objects on public display, and some have private colle ...
displays.molting
In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is a process by which an animal casts off parts of its body to serve some beneficial purpose, either at ...
in stressful conditions; instead of growing larger, it grows smaller with each molt.
Gallery
File:Thylodrias contractus (Motschulsky, 1839).png, ''Thylodrias contractus'' male
File:Thylodrias contractus (Motschulsky, 1839) female.jpg, ''Thylodrias contractus'' female
References
{{DEFAULTSORT:Thylodrias Contractus
Dermestidae genera
Monotypic Bostrichiformia genera
Household pest insects