56 LETTERS ON ENTOMOLOGY. 
They make themselves sometimes the most fan- 
tastical figures, but this only serves to show their 
ingenuity, because they do it for a particular 
purpose ; they are obliged to balance themselves 
in the water, and if too light, they put on a little 
stone ; if too heavy by having imbibed the water, 
they take a light piece of wood or straw. Some 
make very pretty garments by covering them 
with little shells, generally of very small snails 
or muscles. 
We should be very much surprised to see a 
savage, instead of clothing himself with the skins 
of what he kills, covering himself with the living 
animals ; for instance, with squirrels or foxes ; 
yet some of these insects actually do it, and cover 
themselves with little muscles, well fastened on, 
and quite alive, though we may easily imagine 
it is not a very comfortable situation. 
All these insects become flies with four wings : 
they first change into nymphs in their coat or 
sheath ; but as they would be liable in this torpid 
state to be devoured by voracious insects, they 
are obliged to stop the ends, which, as the water 
must not be excluded, they effectually do by a 
grating of silk. 
I must not pass over those caterpillars of this 
species which make themselves long silken 
