The Devils' Little Assistances

My mother always says:  
Where there is One, there is a Ton  
and they are truly not very Fun;  
Where there are Two, there is a Few,  
But when you see them, you are Screwed;  
Where there are Three, let them Be  
But come morning light, you will be up in a Tree.  
 
They come in many different shapes  
And many different sises;  
They come in many different colours  
And have many different Brothers.  
They Bite and they crawl  
And you sometimes see them on your bra.  
 

    4/6/13