293 STATE HORTICULTURAL SOCIETY. 



sites to which they are subject will continue to live and multiply. If 

 the cases were destroyed the parasites would be destroyed with them. 



The second method, importing desirable species, is the more hope- 

 ful, because more certainly within control. Instances of successful 

 importations are given in the European parasites of the wheat midge, 

 of the plumcurculio, of the oyster-shell bark louse, of the black scale 

 and of the Australian and New Zealand enemies of fruit pests that 

 have been so troublesome in California, as well as many others. Prof. 

 Riley calls attention to the fact that when an injurious insect ha& 

 reached the zenith of its increase, and the cultivator is driven to 

 taking the most strenuous measurris to destroy it, this is just the time 

 when nature herself steps in and introduces some check which tends 

 to restore the balance. 



Spraying is open to the disadvantage that it has but little cumu- 

 lative effect, but must be kept up from year to year, the application 

 which destroys the pest destroying its parasitic enemies as well. 

 Injurious insects that have been on the destructive march for a series 

 of years will often come to a sudden halt and complete immunity from 

 injury will follow. Sometimes this is the result of climatic conditions, 

 but more frequently it is the consequence of disease, debility and want 

 of proper nutrition, which are necessary corollaries of undue multi- 

 plication. 



Prof. Riley also calls attention to a law of both insect and plant 

 life which will be new to many readers. It is that animals and plants 

 introduced from Europe and Asia into North America show a greater 

 power of multiplication than the indigenous species, and in a large 

 number of instances have taken the place of native forms which have 

 been unable to compete with them in the struggle for existence. On 

 the other hand, our species when taken to Europe are not able to hold 

 their own against the forms native to that continent. The Australian 

 forms are still less able to hold out against those of Europe, and can- 

 not, as a rule, maintain themselves against those of this country. 



Notes on the Insects of Missouri for 1893. 



By Mary E. Murtfeldt, Kirkwo»d, Mo. 



Among the entomological developments of the earlier part of the 

 current year may be noted the appearance of the army worm fLeucania 

 unipunctaj, in such numbers as to justify its appellation, in hay and 

 grain fields contiguous to streams and lowlands, where it caused con- 

 siderable loss. It also occurred in large numbers, together with other 

 cut-worms, in vegetable gardens as well as on the lawns and meadows 



