Book-lice and Bark-lice; Biting Bird-lice 
11 3 
3 - 
4 - 
5 - 
6 . 
Discoidal cell closed 
Discoidal cell open. 
Discoidal cell closed...5. 
Discoidal cell open. ...6. 
Discoidal cell four-sided. Psocus. 
Discoidal cell five-sided. 
Amphigerontia. 
Third posterior cell elliptical. 
C^ecilius. 
Third posterior cell elongated. 
Polypsocus. 
Third posterior cell absent. 
Peripsocus. 
Myopsocus. 
.Elipsocus. 
d, discoidal cell; 1a, 2 a, 3a, posterior cells. 
(After Banks.) 
The few North American species of the true book-lice or Atropidse are 
included in five genera, which may be distinguished as follows: 
The technical terms, hitherto undefined, used in the following table are the following: 
squama, wings in the condition of small scales or pads; hyaline, clear, not colored. 
1. Meso- and metathorax united, no wings. Atropos. 
Meso- and metathorax separate, rudimentary wings...2. 
2. Wings with veins. Dorypteryx. 
Wings veinless, in form of squamae or tubercles.3. 
3. Squamae small, hyaline... Clothilla. 
Squamae in the form of scars. Lepinotus. 
Small tubercles in the place of squamae. Hyperetes. 
The genera Atropos and Clothilla were named for two of the three Fates 
of mythology, and a third genus was named Lachesis for the third Fate, but 
unfortunately the last genus was not a valid one, so the book-lice have lost 
their third Fate, and by the rigid laws of zoological nomenclature can never 
regain her! The few species of these two Fate-named genera are the com¬ 
monest of the book-lice. Atropos divinatoria is the species usually 
found in books. It is about 1 mm. long, is grayish-white, and the small 
eyes show as distinct black specks on the head. It does not limit its feeding 
to the paste of book-bindings, but does much damage to dried insects in 
collections. To this insect has long been attributed the power of producing 
a ticking noise known as the “death-watch,” but McLachlan, an authority 
on the Corrodentia, does not believe that this minute insect “with a body 
so soft that the least touch annihilates it can in any way produce a noise 
sensible to human ears.” A small beetle, called Anobium, is well known 
to make such a ticking (by knocking its head against the wood of door-casings, 
floors, etc., in which it lives) and probably the “death-watch” is always 
made by this beetle. 
Bird-collectors are often annoyed by small, wingless, flat-bodied, swift¬ 
running insects which sometimes escape from the feathers of bird specimens 
to the hands and arms of the collector. Poultry-raisers are sometimes more 
seriously troubled by finding them so abundant on their fowls as to do con- 
