THEIR RELATION TO PLANTS 83 



liquid mess. There is, in consequence, nearly always 

 an appearance of decay associated with the work of 

 such maggots, and that appearance is very real in 

 cases where the wounded surface gives entrance to 

 soft rots of various sorts. As for the leaf miners, their 

 work is not so destructive in character, although natur- 

 ally every injury that impairs the usefulness of the foli- 

 age to the plant, reacts upon the entire organism to 

 some extent. 



There are other maggot-like larvse that work in 

 plant or fruit tissue such as the apple maggot, the 

 orange fruit fly and a considerable number of other 

 fruit flies which, while they seriously affect the com- 

 mercial value of the product, do absolutely no injury 

 to the plant, since neither the seed nor the tree itself 

 is affected. Only the pulpy covering to the seed is 

 harmed and that is of no importance at all to the plant 

 however much it may be to man. 



We have thus reviewed very briefly the various 

 orders of insects, and have called attention very cur- 

 sorily to the kind of injury which is caused by them. 

 From the time it appears above ground to the period 

 of maturity, almost every species of plant serves as 

 food for insects; and if it survives their various as- 

 saults and reproduces its kind, its decay and return 

 to the inorganic constituents from which it made its 

 growth is hastened by yet other species. And that 

 applies as much to the forest giant, aged hundreds of 

 years, as to the humble cabbage plant that runs its 

 course in a single season. 



