FOOD CONSERVATION AND ECONOMIC ENTOMOLOGY 119 



will not recur indefinitely, and even now the prospects for future 

 damage seem to be decreasing in certain sections. Natural ene- 

 mies of the grub will eventually put an end to the present 

 abundance. 



A generalized life cycle of these insects is better shown as 

 given herewith. Later investigations may show that some species 

 have a different life history, but that given applies generally to 

 Iowa. 



First Year. Beetles emerge from soil in May, feed and deposit 

 eggs. Grubs hatch and begin to feed, wintering over in the 

 soil, (1917 in northeastern Iowa). 



Second Year. Grubs feed during the season. The most dam- 

 age to crops is caused in the second year. The grubs winter over 

 in the soil, practically full grown. (1918 in northeastern Iowa.) 

 . Third Year. Grubs feed early in the season, pupate in June 

 or July, changing to beetles a few wrecks later, remaining in the 

 soil over winter. (1919 in northeastern Iowa.) 



Fourth Year. Same as the first. 



In previous outbreaks of white grubs the worst damage oc- 

 curred to com when this was planted on sod ground. Studies 

 have also well determined that the damage is always worst on 

 the rougher land, in tlie vicinity of timber. The beetles feed 

 on foliage in the woods, and deposit their eggs in uncultivated 

 ground near at hand. In northeast Iowa little in,jury occurred 

 ouithe prairie land. 



Wlien white grubs are expected in any particular year in lo- 

 calities where conditions seem to be favorable for the grubs 

 farmers are advised to plow as little sod as possible. Again, corn 

 should not be planted on sod ground in a "grub year." 



Here in Iowa last year it was determined that conditions all 

 pointed toward damage by white grubs in 1918. In May, 1917, 

 the beetles were common in this area, and farmers reported the 

 small white grubs alnindant in the fall. These were plowed up 

 in sod ground. Consequentlj^ a "white gi'ub campaign" was 

 beg-un in 1918. 



Under the food production act the federal department of 

 agriculture has stationed a man in Iowa whose time is devoted 

 entirely to extension work on cereal and forage crop insects. 

 With the help of the county agricultural agents meetings were 

 held in all those counties where severe damage is expected. 

 The county agent planned these gatherings and usually two or 



