CHAPTER IV. 
CHECKS TO INCREASE OF COCCIDIDA, PARASITES, 
ETC. 
Tur Coccidide, like all Homoptera, produce great numbers of 
young ; but their merease does not appear to be as rapid as that 
of some other families. The numbers of some Aphidide or 
Aleurodide produced from a single female in the course of a 
single year have been calculated at hundreds of thousands, if not 
millions ; and as many as eleven generations have been produced 
in little over half a year. Coccids, however, as a rule, do not 
propagate at this alarming rate. Many, if not the great 
majority of them, produce in this country but one generation in 
the year, e.g., Mytilaspis pomorum, Celostoma zelandicum, &e. 
Others, such as Icerya purchasi, breed more often; and probably 
climate has a good deal to do with the frequency, for Mr. 
Comstock says that m the United States Mytilaspis pomorum 
breeds once a year in the North and twice m the South. In 
point of fact, it does not seem possible to lay down any rule on 
the subject. Unfortunately, Jcerya is not only a frequent 
breeder, but also the most destructive insect of the family in 
New Zealand. , 
The number of young produced by each female seems also to 
vary. The author has counted from 80 to 80 eggs in the 
puparium of Mytilaspis pomorum ; as many as 350 in the ovisae 
of Icerya purchasi, and about the same number of Cewlostoma 
zelandicum: and a female of Lecanium hesperidum examined in 
spring contained 93 embryos. These figures do not denote any 
remarkable fertility ; but, as in the majority of cases males are 
but seldom met with, sometimes even entirely unknown (e.g., 
Lecanium hesperidum), it follows that nearly every insect is capable 
of propagation, and the increase in numbers is therefore more 
rapid than might be anticipated otherwise. How the females 
in the species apparently destitute of males are enabled to pro- 
