BUGS. 217 



giving it a tessellated appearance similai- to the plates on the back of the common box 

 tortoise. About fifteen or sixteen species are known, which have been obtained from 

 almost as many regions of America, Africa, Europe, Asia, and Australia. These all 

 have a more or less waxy covering for the protection of the body in the female, and 

 this substance has been employed to some extent in the fine arts. 



A peculiar form hitherto found only in the United States stands in great contrast 

 with all of the above, and as a conspicuous member of this family deserves to be noticed. 

 It is the Pulvinaria immmerdbilis of recent authors, and was first made known by 

 Mr. S. S. Rathvon, of Lancaster, Pa., who discovered it in great numbers upon linden 

 trees growing in that city. It has been since found in many parts of the middle, 

 northern, and northwestern states, more commonly upon the soft maple. Mr. Putnam 

 of Davenport, Iowa, made a special study of its life history and structure, and by his 

 patient labor has given a fuller account of this species than exists of any other of our 

 North American forms. 



During some years it is exceedingly abundant upon the maples lining the streets in 

 the city of Baltimore, and forms a conspicuous object projecting from the twigs and 

 leaves. When fully developed it is one-fourth of an inch in length, resembling a little 

 ball of cotton floss, with the dark dried scale on the front, arid when settled in closely 

 packed patches it gives the limbs of trees an appearance of being loaded with pellets 

 of loose cotton. A close examination of this cottony mass in the month of May dis- 

 closed multitudes of exceedingly minute, white eggs entangled all through it. In about 

 three weeks the eggs appear somewhat darkened in color by the embryo showing 

 through the transparent shell and begin to give forth the young larvae. These are 

 active little creatures, with six legs, and of an elongated oval form, rather depressed 

 and sharp-edged. They soon find a place upon which to settle, either upon the twig 

 or leaf, and after withdrawing their slender rostral bristles from the loojj in the abdo- 

 men, thrust them through the tender bark and become fixed for the remainder of their 

 short lives. 



Advancing a step farther we reach the most important gi-oup of this family, the 

 true Coccina. Here we have forms which preserve the distinctly segmented body and 

 capacity for motion throughout all stages of their existence. In other words they 

 are a grade higher than either of the other alliances. In only a very few species do 

 they become covei-ed by a hardened scale and fixed to a single spot ; but because of 

 these exceptions a modification of the terms distinctive of the sub-family becomes 

 necessary, and thus the group is limited by only a very small number of characteristics. 

 The principal of these is found in the many-jointed labium of the female, besides the 

 persistent distinctness of the segments alluded to above. In this sex also the antennae 

 are composed of from six to ten joints in the adult, and six only in the larvae. 



The adult males differ from Zecanium, chiefly in having shorter attachments to the 

 body, with large wings and three-jointed poisers. In a few species the wings are absent. 



To this sub-family belongs that important and precious insect, the Coccus cacti of 

 authors, which yields the highly pi-ized Cochineal of commerce. This is the most 

 valuable insect in existence, and has superseded in large measure the use of various 

 other species of this group, some of which had been employed as a dye from a period 

 dating back to the time of Moses. The Phoenicians were famous for the rich red of 

 their garments, and it is no doubt due to their acquaintance with the Kermes of the 

 Mediterranean borders that they were able to obtain such celebrated crimson and 

 scarlet dyes. 



