HOUSEHOLD INSECTS 273 



Biselliella makes no case like pellionella ; it feeds on 

 similar substances, with the addition of cobwebs, and as 

 proof that the insect obtains all necessary nourishment 

 from this curious fare, the larvae have been raised on cob- 

 webs alone. The full-grown larva pupates in a silken 

 cocoon to which bits of wool are attached, giving it some- 

 what the appearance of the larval case of pellionella. The 

 tapestry moth, Tinea tapetzella, attacks coarser material 

 than its relations, and damages them rather by constructing 

 a series of tunnels through them than by eating them. 



Two STARCH-LOVING INSECTS 



A common household insect which is probably known 

 by sight to everyone, though its identity may be a mystery, 

 is the book louse, Atropos divinatoria (fig. 74). A very 

 small, nearly colourless, soft-bodied, wingless insect, it is 

 often to be found frequenting old books and papers, for 

 the sake of the starchy paste used in binding, etc. Minute 

 and soft-bodied as this insect is, it nevertheless has the 

 power of making a tapping sound, probably by beating 

 its head against woodwork, and, needless to say, like the 

 true "death watch," it has given rise to much supersti- 

 tion. Lastly, let us mention the silver fish, Lepisma 

 saccharina (fig. 75), first noticed by Hooke in 1665. It is 

 a great enemy of all goods containing starch. It is fish- 

 like in form, scaly, about a third of an inch long, and silvery 

 in colour. On the head are a pair of relatively long 

 antennae, and from the hinder end of its body three long, 

 soft bristles project. An allied species, Lepisma domestica, 

 has earned the name of " fire brat " from the curious habit 

 it has developed of disporting itself in places so warm that 

 they would be fatal to other insects. 



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