14 INSECTS AFFECTING THE ORANGE. 



DIVISION INTO SUBFAMILIES. 



The species of Coccidae, according to their varied forms and the diverse 

 nature of their coverings, are divided into several groups or subfamilies. 



Three groups are represented in the southern United States, and em 

 brace all the species doing injury to orange trees. The characters 

 given below will suffice for the proper arrangement of the species falling 

 within the scope of this treatise. 



I. DiASPiN^. — This subfamily embraces those species which form a 

 thin, horny scale, supplemented by the molted skins of the insect. 

 Example, the Long Scale of the Orange, Mytilaspis gloverii. 



II. Lecanin^. — The species of this division form no true scale ; they 

 are either naked or covered with a thick coating of waxy material. 

 The naked species have, however, toughened skins, which, after the 

 death of the insect, remain adhering to the bark, and then somewhat 

 resemble the scales of the Diaspinse. Example, the Turtle-back Scale, 

 Leca nium h espe rid urn . 



III. Cogging. — This division includes soft-bodied Bark-lice, called 

 "Mealy-bugs" because of their loose coverings of white, fibrous wax, in 

 the form of a powder, or of long and delicate plates and filaments, 

 easily destroyed by a touch. Example, the common Mealy-bug, Dacty- 

 lopius destructor. 



In the first of these groups (Diaspinse) the change from an active, 

 roving larva, possessed of legs, to a fixed and memberless, sack-like 

 animal, takes place very soon after birth. The scale also is a complete 

 and separate structure, permanently fastened to the bark, and large 

 enough to include not only the body of the mother insect, but also her 

 eggs. 



In the second group (Lecaninie) the form of the larva is retained 

 much longer than in the first group, and the insects, though very slug- 

 gish in habit, do not become absolutely fixed upon the bark until they 

 are distended with eggs or young. The legs also are not lost, but 

 gradually become useless as the insect increases in size, and are finally 

 lost to sight under the swollen body. 



In the third group (Ooccinie) the form of the larva is retained by the 

 females through life, and is obscured, but not altered, by the formation 

 of an egg-sack, or by light coatings of wax.* The organs of locomotion 

 are retained, and the females in most of the species move about freely, 

 even after they have begun to produce young. 



Thus in structure and habits the Diaspiuae differ most widely from 

 other insects, the Cocciuse least, while the Lecanime hold in this respect 

 an intermediate position. 



'Except in Kermes, a geuue with which orange-growers are not likely to become 

 concerned. 



