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Bark Lice

Emilie Bess and Kevin P. Johnson
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taxon links [up-->]Hemipsocidae [up-->]Myopsocidae [up-->]Psocidae [up-->]Psilopsocidae [down<--]Psocomorpha Interpreting the tree
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Containing group: Psocomorpha


Infraorder Psocetae includes the families Hemipsocidae, Myopsocidae, Psilopsocidae, and Psocidae, which comprise about 70 genera and 1100 species worldwide.  These bark lice live in dead foliage, on bark, or on stone surfaces. They are 2-8 mm long and eat lichens, algae, and fungus.



General Characters

Discussion of Phylogenetic Relationships

The monophyly of the four families of Psocetae is strongly supported with molecular data (mtDNA genes 12S, 16S, and COI, and 18S rDNA; Johnson & Mockford 2003, Johnson et al. 2004).  Morphological data, however, led Yoshizawa (2002) to exclude Hemipscoidae from the infraorder.  He erected the infraorder Hemipsocetae to include Hemipsocidae alone, based on four characters: absence of the epistomal suture, broadened first axillary sclerite, two-branched M vein in forewing, and CuA1-M crossvein in forewing.

The classification used here is based on molecular data and places family Hemipsocidae as sister to family Psilopsocidae within infraorder Psocetae (18S rDNA; Johnson et al. 2004).

Other Names for Psocetae


Johnson, K. P. & E. L. Mockford. 2003. Molecular systematics of Psocomorpha (Psocoptera). Systematic Entomology 28: 409-40

Johnson, K. P., K. Yoshizawa, and V. S. Smith. 2004. Multiple origins of parasitism in lice. Proceeding of the Royal Society of London B 271: 1771-1776.

Lienhard, C. and C. N Smithers. 2002. Psocoptera (Insecta) World Catalogue and Bibliography. Muséum d'Histoire Naturelle, Geneva, Switzerland.

Mockford, E. L. 1993. North American Psocoptera (Insecta). Gainesville, Florida: Sandhill Crane Press.

Mockford, E. L. 2005. Order Psocoptera: Psocids. Pp. 341-355 in C. A. Triplehorn and n. F. Johnson (eds.) Borror and DeLong's Introduction to the Study of Insects. Belmont, California: Thomson Publishing.

Smithers, C. N. 1996. Psocoptera. Pp. 1-80, 363-372 (Index) in A. Wells (ed.) Zoological Catalogue of Australia. Vol. 26. Psocoptera, Phthiraptera, Thysanoptera. Melbourne: CSIRO Publishing, Australia.

Yoshizawa, K. 2002. Phylogeny and higher classification of suborder Psocomorpha (Insecta: Psocodea:'Psocoptera'). Zoological Journal of the Linnean Society 136: 371-400.

Yoshizawa, K. 2005. Morphology of Psocomorpha (Psocodea: 'Psocoptera'). Insecta Matsumurana 62: 1-44.

Title Illustrations
Click on an image to view larger version & data in a new window
Click on an image to view larger version & data in a new window
Scientific Name Blaste sp.
Location Nokonoshima Island, Kyushu, Japan
Specimen Condition Live Specimen
Identified By K. Yoshizawa
Life Cycle Stage adult
View dorsal
Size 3mm
Copyright © 2006 Kazunori Yoshizawa
Scientific Name Cerastipsocus venosus
Location Vernon, Vt.
Specimen Condition Live Specimen
Behavior aggregation
Life Cycle Stage nymphs
View dorsal
Copyright © Tom Murray
Scientific Name Psococerastis sp.
Specimen Condition Live Specimen
Identified By K. Yoshizawa
Life Cycle Stage adult
View lateral
Size 4mm
Copyright © 2006 Kazunori Yoshizawa
About This Page

Emilie Bess
Illinois Natural History Survey, Champaign, Illinois, USA

Kevin P. Johnson
Illinois Natural History Survey, Champaign, Illinois, USA

Correspondence regarding this page should be directed to Emilie Bess at and Kevin P. Johnson at

All Rights Reserved.

Citing this page:

Bess, Emilie and Kevin P. Johnson. 2009. Psocetae. Bark Lice. Version 25 March 2009 (under construction). http://tolweb.org/Psocetae/30220/2009.03.25 in The Tree of Life Web Project, http://tolweb.org/

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