Bactridium atratum

Bactridium LeConte 1861


Bactridium belongs to the heterogeneous tribe Europini, and is closely allied to Leptipsius and Pycnotomina. Currently, Bactridium species determination is difficult, if not impossible. There are no published data or hypotheses about the relationships within the genus. A revision is currently in preparation by the first author. The type species is Bactridium ephippigerum.


Bactridium can be distinguished by the following features: neck constriction absent, antennal club one-segmented, and femoral lines well-developed.


Bactridium species are usually collected under the bark of various hardwood trees, especially Quercus spp., where at least some species feed upon ascomycete fungi (Lawrence 1991), including spores and stromatal tissue. They also have been collected under bark of Acer, Carya, Chayote, Castanea, Ulmus, Morus, Liquidambar, Rhus, Pinus, Bursera, and Koelreuteria. Bactridium species are sometimes collected with pitfall traps, log emergence traps, or Berlese funnel extractions from fungusy plant material (TCM, pers. obs.). Some Bactridium are caught almost exclusively in intercept traps located in the forest canopy (Ulyshen & Hanula, 2007).


The genus is widely distributed in the New World. Species have been described from the United States south to Brazil. One species, Bactridium insularis, is found on the Galapagos Islands (although its generic placement is doubtful). Bactridium humile, B. orientalis, and B. parvum are only known from Indonesia and Papua New Guinea. However, these species likely do not belong within the modern concept of Bactridium (TCM, pers. obs.). It is possible that true Bactridium is restricted to the New World.

List of New World Species


Reitter 1876
Reitter 1876
Fall 1917
Casey 1916
Sharp 1900
(Guêrin-Méneville 1837)
(Reitter 1872)
(Reitter 1872)
(Reitter 1872)

Not photographed:

Suggested References

Casey 1916 - most recent revision of genus

Lawrence 1977 - description of Bactridium ephippigerum larva, first generic host associations, comments about Monotomidae biology

LeConte 1861 - original description of genus

Sen Gupta 1988 - redescription of genus - characterization of modern concept of genus