8 THE COCCIDAE 



a desire to get out and wander. It acts upon them suddenly as 

 if they were seized with hysteria, they become not only active but 

 they literally swarm out over the branches of the host-plant until 

 frequently it is completely covered. The function of this migration 

 period is apparently for the dissemination of the species and to 

 find an unencumbered portion of the host-plant where the nymph 

 can attach itself and begin to draw food. 



The generalized coccids are active throughout their entire 

 nymphal life and in some even throughout their entire life as the 

 females of the genus Orthezia. The great majority are quiescent 

 during the adult stage. It would not be strange, therefore, to find 

 that the length of the active period had been shortened and the 

 quiescent period lengthened from just the adult condition to 

 practically the entire life of the insects. The quiescent period in 

 many specialized coccids begins just as soon as the migrating 

 nymphs of the first nymphal period fix themselves to the host- 

 plant. In many species the appendages, including the legs and 

 antennae, and even the mandibles and maxillae in the male, but 

 not the labium or rostrum, are lost at the first molt, so that the 

 animals are capable of only slight movements. 



The males are easily identified after their entrance into the 

 quiescent period which is after the first molt in the Eriococcinae, 

 because the mouth-parts are wanting. They can usually be identi- 

 fied a short time before the first molt in mounted specimens. The 

 developing mandibles and maxillae of the female which are func- 

 tional during the second stage can be identified as a coiled watch- 

 spring-like structure within the cuticle on each side of the rostrum. 

 These coiled structures, since the mandibles and maxillae are 

 wanting in the second and following stages of the male, are never 

 present in the first nymphal stage. 



The nymphal males usually molt about four times and there 

 are four nymphal stages. The young nymphs form a cocoon or 

 scale from threads of wax at sometime before or near the beginning 

 of the quiescent period. This quiescence may begin early in the 

 second nymphal period or it may be delayed to as late as the 

 fourth nymphal period. The molted skins are usually pushed out 

 under the nymphal case or scale as they are cast. The nymphal 

 appendages and legs are lost at the molt when the male enters the 

 quiescent period. The appendages of the adult, including a single 

 pair of wings in most males, are developed from imaginal discs. 

 It has been maintained by some that the male coccid passes 

 through an indirect or complete metamorphosis. Their determi- 

 nation is based upon the presence of a quiescent period during the 



