INTRODUCTION. 



ENTOMOLOGICAL CALENDAR. 



To the year 1884 we can not accord any peculiar distinction in the 

 annals of economic entomology in Illinois, unless we consider the 

 general prevalence of the soft maple bark louse {Pulvinaria innum- 

 erahllis) and a notable outbreak of the grass worm [Lapluigma frugi- 

 perda) as especially remarkable events. The general damage to the 

 crops by insects, was, as a whole, decidedly below the average, not 

 a single one of the great scourges of agriculture having attracted 

 general attention or done conspicuous damage except in one or two 

 instances and in limited localities. I wish I might believe that this 

 fact was due in any considerable measure to the progress of the 

 popular knowledge of economic entomology and to an increased dis- 

 position to apply its resources to the war against our insect enemies, 

 but I judge that it is to be attributed to providential rather than to 

 human interposition. 



The average weather of this season and the preceding, inclining 

 in both to extraordinary moisture, except during the period when 

 the Hessian fly is peculiarly subject to injury by drouth, has supplied 

 conditions on the whole unfavorable to a high rate of multiplication 

 among those species peculiarly susceptible to meteorological influ- 

 ences. 



The Hessian fly, so destructive last year throughout Southern 

 Illinois, was so far decimated by its parasites and by the long 

 drouth and heat of summer, that we have not encountered it in 

 destructive numbers except in Clark county, in Eastern Illinois, in 

 localities where it did not last year prevail. The fact that the fly 

 occurred here when the weather was not different from that of more 

 southerly localities infected last year, shows that we owe the arrest 

 of its ravages in these localities less to the weather than to other 

 causes, — chief of which are, of course, its parasites. 



*Under the above head it is proposed to give, ea.(i\ year, a summary of the principal 

 events of interest in the field of economic entomology within the State, with principal 

 reference to the great insect pests whose numbers vary widely from year to year, so that 

 these introductions may afford a continuous history of the oscillations of the most im- 

 portant species. Here also will be introduced those species first recognized as injurious to 

 agriculture during the year which the report covers, where these seem of sufficient im- 

 portance to deserve special mention in this connection. 



