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Emilie Bess and Kevin P. Johnson
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taxon links [up-->]Bryopsocidae [up-->]Mesopsocidae [up-->]Philotarsidae [up-->]Trichopsocidae [up-->]Pseudocaeciliidae [up-->]Peripsocidae [up-->]Elipsocidae [up-->]Ectopsocidae [up-->]Lachesillidae [up-->]Calopsocidae Monophyly UncertainMonophyly UncertainMonophyly UncertainMonophyly UncertainMonophyly Uncertain[down<--]Psocomorpha Interpreting the tree
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The root of the current tree connects the organisms featured in this tree to their containing group and the rest of the Tree of Life. The basal branching point in the tree represents the ancestor of the other groups in the tree. This ancestor diversified over time into several descendent subgroups, which are represented as internal nodes and terminal taxa to the right.

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Containing group: Psocomorpha


Infraorder Homilopsocidea contains ten families: Bryopsocidae, Calopsocidae, Ectopsocidae, Elipsocidae, Lachesillidae, Mesopsocidae, Peripsocidae, Philotarsidae, and Pseudocaeciliidae, and Trichopscidae.  These families comprise about 90 genera and 1500 species worldwide.

Members of this infraorder are very diverse morphologically and biologically.



(from Yoshizawa 2002):

General Characters

(from Yoshizawa 2002):

Discussion of Phylogenetic Relationships

Monophyly of Infraorder Homilopsocidea is uncertain.  Morphological data support monophyly based on the synapomorphic characters listed under Characteristics (Yoshizawa 2002).  Molecular data, however, divide the infraorder: one clade contains families Calopsocidae, Philotarsidae, and Psedocaeciliidae, and a series of small clades (sister to Infraorder Caeciliusetae) contain families Ectopsocidae, Lachesillidae, Elipsocidae, and Mesopsocidae (Johnson et al. 2004).  Further work is needed to clarify relationships within the infraorder.


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.

Title Illustrations
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Scientific Name Mesopsocus unipunctatus
Specimen Condition Live Specimen
Identified By K. Yoshizawa
Sex Female
Life Cycle Stage micropterous adult
View anterolateral
Size 3mm
Copyright © 2006 Kazunori Yoshizawa
Scientific Name Heterocaecilius solocipennis
Location Japan
Specimen Condition Live Specimen
Identified By K. Yoshizawa
Life Cycle Stage adult
View lateral
Size 3mm
Copyright © 2006 Kazunori Yoshizawa
Scientific Name Ectopsocus
Location Boxborough, Ma.
Comments 11/26/2006
Specimen Condition Live Specimen
Life Cycle Stage nymph
View dorsal
Copyright © Tom Murray
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. Homilopsocidea. Version 25 March 2009 (under construction). http://tolweb.org/Homilopsocidea/14479/2009.03.25 in The Tree of Life Web Project, http://tolweb.org/

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This page is a Tree of Life Branch Page.

Each ToL branch page provides a synopsis of the characteristics of a group of organisms representing a branch of the Tree of Life. The major distinction between a branch and a leaf of the Tree of Life is that each branch can be further subdivided into descendent branches, that is, subgroups representing distinct genetic lineages.

For a more detailed explanation of the different ToL page types, have a look at the Structure of the Tree of Life page.

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