MALLOPHAGA AND ANOPLURA - BITING AND SUCKING LICE

Lice are small wingless parasites with dorsoventrally compressed bodies 1-5 millimetres in length.  They have been separated into two groups, the biting lice (Mallophaga) and the sucking lice (Anoplura).  The head of the biting louse is usually as broad as, or broader than, the thorax while in sucking lice it is usually narrower.  Lice cannot be specifically identified under field conditions.  Biting lice are primarily avian parasites but many have been reported from mammals.  Sucking lice are exclusively mammalian parasites.

Scholten (1962) found various species of lice on wildlife of Manitoulin Island.  He collected biting lice from skunk, short-tailed weasel and white-tailed deer and sucking lice from flying squirrel, red squirrel, chipmunk, a variety of mice, groundhog, deer and bear.  Watson and Anderson (1975) found three species of lice on deer of Long Point, Ontario.  Addison, Pybus and Rietveld (1978) found biting lice on bear from North Bay.

Both types of lice spend their entire life on the host.  The eggs (or nits) are small, white and elongate and are laid individually on the hairs or feathers.  These hatch into the first immature stage (larva) which appears similar to the adult but is usually smaller and lacks the adult colouration and genitalia.  There are generally three to four larval stages which become progressively larger than the first larval stage.  The moult to the adult results in the formation of characteristic adult size and colouration.  All stages feed on the host.

Biting lice generally feed on hair, feathers and epidermal debris.  This makes them poor vectors of disease although in high numbers they may cause much irritation to the host.  Sucking lice, on the other hand, pierce the skin and suck blood.  This feeding behaviour facilitates passage of disease agents but there appear to be no recent records of louse-bome diseases in Ontario.  Sucking lice often cause allergic reactions.  Heavy infestation with lice may cause anaemia and possibly death.  Death usually is restricted to hosts that are young or in poor condition for reasons other than the presence of lice.

Louse populations undergo seasonal fluctuations.  These may vary according to the biology of specific lice and of the hosts which are infected.  Numbers of lice on wildlife are usually highest during late winter and spring.  During the summer and autumn lice are generally absent or extremely rare.

Selected References:

Addison, E.M., M.J. Pybus and H.J. Rietveld. 1978.  Helminth and arthropod parasites of black bear, Ursus americanus, in central Ontario.  Can.  J. Zool. 56:2122-2126.

Chandler, A.C. and C.P. Read. 1961.  Introduction to parasitology with special reference to the parasites of man. 10th ed.  John Wiley and Sons, Inc., New York.

Scholten, T.H. 1962.  Some arthropod parasites of mammals of Manitoulin Island, Ontario.  M.Sc. Thesis, University of Guelph, Guelph.

Watson, T.G. and R.C. Anderson. 1975.  Seasonal changes in louse populations on white-tailed deer (Odocoileus virginianus).  Can.  J. Zool. 53:1047-1054.