G4 



^nd these species comprised two-thirds of the collections made in 1914. 

 L. rugosa, L. anxia and L. nitida are also dominant species in northern 

 Illinois. \L. rugosa feeding on poplar and willow, L. nitida on hazel, and 

 L. anxia on willow, poplar, apple, oak and linden ; L. fusca, L. inversa 

 ,and L. drakii are numerous in northern and central Illinois ; L. fusca 

 feeding on poplar, willow, oak, hickory, ash, elm, apple and walnut ; 

 L. inversa on apple, elm, blackberry and ash ; L. drakii on willow, 

 poplar, oak, elm, hazel and blackberry. The common species in 

 ■Central and Southern Illinois are : — L. hirticula on oak, hickory, 

 blackberry and other plants ; L. fervida on oak, hickory, persimmon 

 and willow. The southern species are : — L. forbesi on cherry, peach, 

 .and apple ; L. micans on persimmon and oak ; L. bipartita on willow, 

 hickory, and oak ; L. fraterna, L. profunda, L. corrosa and L. forsteri, 

 on oak, persimmon, and hickory ; L. crenidata on persimmon, willow, 

 and hickory ; L. delata on oak and hickory ; L. praetermissa on oak, 

 willow and hickory ; and L. vehemens, the food-plants of which are 

 unknown. Tables are given setting forth the seasonal succession of the 

 species in the different districts for the years 1907-1910, and the dates 

 of collection for various sections of the State. The periods of extra- 

 ordinary abundance of a species in any locality or district shows little 

 correspondence with any life-cycle. Extensive parasitism of adults 

 and larvae by insects. Annelids, Protozoa and fungi, produces wide- 

 spread and destructive epidemic diseases, a knowledge of the prevalence 

 and status of which is essential to any safe prediction of periods of 

 •destructive abundance of these beetles. In America the so-called 

 " flight year " of the beetles may be predicted for any locality and 

 measures taken accordingly, but in Europe no parasites of the insects of 

 this group are known and there is comparatively little to interfere with 

 the periodical recurrence of seasons of destructive abundance. It is 

 possible that parasites, especially fungi, may be cultivated and dis- 

 tributed and thus assist materially in the control of the insects. A 

 recently discovered Annelid parasitic on the grubs, which is the cause 

 of epidemic destruction among them, may be readily bred and grown 

 in great abundance on raw egg. 



Forbes (S. A.). The Influence of Trees and Crops on Injury by White 



Grubs. — Twenty-ninth Report of the State Etitomologist of the State 

 of Illinois, Vrbana, 1916, pp. 66-70. 



In fields having trees within or on their borders or within less than 

 an eighth of a mile, white grubs of the genus Lachnosterna {Phyllo- 

 phaga) were found at an average rate of 39*17 to the mile ; where 

 trees were more than an eighth and less than a quarter of a mile away, 

 the grubs averaged 17"83 ; more than a quarter of a mile and less than 

 half a mile, 15"94 ; half a mile or more, 14-4, More eggs were found 

 to be laid in pasture than in any other crop, followed by wheat and 

 oats, fallow ground, clover, maize and other meadow crops in that 

 order. It was found as a result of the extraordinary injury by white 

 grubs in 1912 in Northern IlHnois, that of forty-four fields injured, 

 though 80 per cent, were under maize in 1912, only 5 per cent, carried 

 that crop in 1911 ; whereas only 14 per cent, were under grass 

 in 1912, and 43 per cent, had borne that crop in 1911 ; none of the 

 injured fields was under oats, rye or barley in 1912, but 52 per cent. 



