70 INSECTS AFFECTING THE ORANGE. 



Of all its enemies, the most efficient destroyers of the Scale insect are 

 its hymenopterous parasites ; several species of which have already been 

 noticed, each under the head of the particular Coccid with whose life 

 history it is closely connected. Fig. 1 on Plate VI represents the com- 

 mon parasite (Aphelinus mytilaspidis) of the Apple Scale. These minute 

 four- winged flies bore through the scale and deposit within a single egg. 

 The little grub hatching from this egg feeds upon and destroys the 

 occupant of the scale and completes its own transformations in its 

 place. When fully adult the parasite emerges through a round hole 

 eaten in the shell, leaving behind an empty domicile to serve as a 

 shelter for the mites. 



The numerous species of these parasites, although not invariably con- 

 fined in each case to a single species of Bark-louse, have distinct meth- 

 ods of attack from which they do not vary. Thus the Long and the 

 Purple Scales are parasitized at about the time of impregnation of the 

 females, or when they are not more than one-half their adult size, and 

 the young Hymenopteron is developed entirely within the body of the 

 Coccid. The skin of the latter hardens when life is extinct, and doubly 

 protects the parasite during the latter part of its larval and in its pupa 

 stage. The parasite of the Chaff Scale makes its attack at a later stage, 

 often when the scale is full of eggs, and its larva does not enter the 

 body of the Coccid, but feeds upon it and the eggs indiscriminately, oc- 

 casionally devouring the eggs alone and leaving the mother Coccid un- 

 touched. Its pupa is formed naked within the scale, and has only such 

 protection as this affords the Coccid and its eggs. In individual num 

 bers these hymenopterous parasites abound to such an extent that rarely 

 less than 25 per cent, and often more than 75 per cent, of the scales are 

 attacked by them, and the work of destruction accomplished through 

 their agency alone equals if it does not excel that of all other enemies 

 combined. Doubtless without their aid the culture of the Orange and 

 related trees would, in Florida at least, become impracticable. 



INSECTS OF THE ORDER HYMENOPTEBA. 



ANTS. No species of field-ant, in Florida at least, is in any sense 

 predatory upon Scale-insects. With the hard-shelled Diaspina3 ants do 

 not concern themselves, except that most of the carnivorous kinds will 

 feed upon the contents of a scale which they chance to find torn from the 

 bark. Many of the softer CoccidaB are attended by ants and to some 

 extent protected by them, for the honey which they produce, and upon 

 which the ants feed greedily without in the slightest degree harming or 

 even disturbing the Coccids themselves. 



The Chinese, it is said, have an ant which is really predatory upon 

 Scale-insects, and which they colonize in some manner about their trees 

 for the purpose of clearing them of these pests. If such a species ex- 

 ists, its importation to this country would be a great boon and could 

 undoubtedly be accomplished. There is in fact nothing impracticable 



