Dale Fort Blog Number 8

28 05 2012

Another article about another of the little-sung creatures you share your home with


The scientific name is Liposcelis corrodens.

Lipos = Greek for fat

Celis = koilia = Greek for belly

Corrodentia = Latin: To gnaw to pieces

The fat-bellied book-chewer

They belong to a group of insects known as “Psocids” pronounced ‘So-sids’

They are to be found in the cleanest of houses and are benign relatives of the parasitic lice that feed on blood or skin.  They are not dangerous to humans (but you probably wouldn’t want to eat them, see below).

   Lipocelis corrodens is non-sexual, there are no male insects.  Females lay unfertilized eggs that develop into genetically identical females (parthenogenesis).  In appropriate conditions a booklouse can lay 4 eggs a day.  This might not appear to be many but from the mother’s point of view an epidural might seem appropriate because the eggs are about a third as big as the adult.  Virtually transparent, baby Psocids hatch out after 1-2 months. The adult is pale, inconspicuous and about a millimetre long.  Black or very dark brown individuals (most often found on walls behind picture frames in my house) are probably a related species Lipocelis bostrychophila.  This latter species is thought to be commonest in the UK.

They are to be found everywhere in the world.  An absence of wings, coupled with the fact that on a bad day they could be outrun by lichens might lead us to question how they have managed this.  The answer is probably that they are dispersed by air currents.  A study in 1945 found them persisting as low-level aerial plankton.

Most books are made from wood which is not an easy thing to subsist on.  Wood- eating animals like termites can only digest it with the aid of the complex community of micro-organisms that dwell in their guts (baby termites inoculate themselves with these organisms by licking their mother’s bottoms and starve if they don’t).  Booklice can’t eat books directly but chomp instead upon the moulds and fungi that can.  Two stiff rods support the head while the biting jaws chew up the food.  It could be argued that booklice are a force for book-conservation because they remove paper and gum digesting fungi.  In the long run, it’s probably better to get rid of both.  An easy way to do this is to heat and desiccate them (a hair dryer will do the job).  You should think carefully before applying this treatment to your First Folio Edition Shakespeare.

The other place you might find these animals is in stored foods, especially flour.  They feed on the flour and favour the dark warm crevices found in paper packages in kitchen cupboards.

In 1996 Bryan Turner of King’s College purchased packets of flour in pairs from a variety of supermarkets.  One of each pair was put in a kitchen cupboard and the other was sealed in a plastic bag.  After a week the kitchen packet was also sealed in a plastic bag.  All the samples were then kept at room temperature for three months.  Upon examination, 17% of the kitchen packets (22 out of 133) were infested.  None of the control packets (those sealed immediately) were.

Some years ago I discovered an infestation in one of our cupboards.  I threw away the contents and disinfected the cupboard.  An electric fan-heater was then directed into the interior to make it hot and dry.  To this day, the Psocids have kept away.  We moved the flour to a higher, drier, lighter place and it seems to work.  Another useful tip is to actually use the food items you store.  If something’s 7 years after its “best by” date it’s almost certainly being eaten by something other than you.




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