10 INSECTS NOXIOUS TO AGRICULTURE. 



from Hymenopterous parasites, of which some account will be 

 found in a subsequent chapter (Chap. IV.). 



The effects of the Coccididse are not confined altogether to 

 damage to plants : there are some species producing materials 

 useful to man. For example, Coccus cacti produces cochineal; 

 Carteria lacca produces shellac ; Ericerus pe-la is used by the 

 Chinese for candles : and others might be mentioned. But, so 

 far, no New Zealand species appears to be of any commercial 

 use. Dactylopius alpinus makes a rather rich red dye in alcohol ; 

 C&lostoma zealandicum constructs thick, waxy coverings, which 

 might possibly be turned to some account ; but even these are 

 probably not worth much. 



Groups. 



The groups into which the Coccididse are, in this work, 

 divided are as follow : 



1. Female insects constructing for tb em- 

 selves shields composed partly of 

 secretion, partly of the pellicles dis- 

 carded from earlier stages; abdomen 

 not cleft ; legs lost at full growth. DIASPIDIN.E. 



.2. Female insects naked, or covered with 

 shields of secretion, either waxy, 

 horny, cottony, or felted ; abdomen 

 in all stages cleft ; legs either lost 

 or retained at full growth. LECANIDIN^E. 



3. Female insects naked, or covered with 



shields of waxy secretion ; abdomen 

 of larva ending in prominent pro- 

 cesses, abdomen of adult cleft ; legs 

 either lost or retained at full growth. HEMICOCCIDJX^ 



4. Female insects naked, or covered with 



secretion either w r axy, cottony, or 

 felted ; abdomen in all stages end- 

 ing in prominent processes ; legs 

 either lost or retained at full growth. COCCIDIN/E. 



Life-history. 



The life-history of the insects in the above groups is as 

 follows : 



All of them pass through four stages of existence : 1, the 



