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JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 9 



fields being cleared of a heavy infestation of grubs by permitting the 

 chickens the run of the field during cultivation. 



Fall Plowing. — Plowing just previous to the time the grubs go 

 deep into the ground to pass the winter will destroy many of them and 

 should be practiced whenever possible but it should not be considered 

 a panacea for the grubs. Fall plowing the year the grubs are changing 

 to beetles, especially early fall plowing and the sooner after July 15 

 the better, is very effective in destroying the grubs as they are trans- 

 forming to pupse, the pupse themselves and the recently issued beetles. 

 If the cells containing prepupse, pupse and recently issued beetles are 

 broken, the insect within will almost invariably be destroyed and it is 

 therefore important to use a plow which will break up the soil as it is 

 overturned, or if this is not possible the ground should be deeply 

 disked after plowing in order to break up the soil. In 1916 early fall 

 plowing will be especially helpful in the localities where grubs were so 

 destructive in 1915 and where entire communities can follow this 

 practice much benefit will result. 



Rotation of Crops.— A rotation to avoid grub injury is of greatest 

 importance but it is essential that the farmer be acquainted with the 

 life-history and habits of the insect in order to intelhgently adopt a 

 rotation which will not only be effective in preventing grub injury but 

 which will be best suited to his conditions. We know the beetles 

 prefer a ground covered with vegetation for the deposition of their 

 eggs, hence, other conditions being equal, most of the eggs will be laid 

 in timothy, blue grass, and small grain fields. Consequently, the year 

 following a large flight of beetles, such ground should not be planted 

 to the more susceptible crops such as corn and potatoes. On the other 

 hand, land which was in corn or other wide-row crops and kept thor- 

 oughly cultivated during the flight of the beetles will ordinarily have 

 few grubs and hence such land should be used the following year for the 

 crops most susceptible to grub injury, that is for corn, potatoes, beans, 

 etc. A rotation of oats, clover and corn has proven very satisfactory 

 in some sections. Our observations indicate that ground with a 

 heavy stand of pure clover when the beetles are flying will ordinarily 

 contain few grubs since the beetles will not seek such land for egg- 

 laying. Clover, if planted in the fall and allowed to make a good 



Explanation op Plate 14. 

 Plate 14. a, Lachnosterna grandis grub, h, L. grandis 9 pupa, c, L. prunina 

 c? adult, d, L. gibhosa in copula, e, L. arcuata egg recently laid; e fully swollen, 

 /, L. sp. grub in prepupal stage, g, L. gibhosa pupa in pupal cell, h, Diplotaxis 

 eggs, several eggs in a ball of earth in a single cavity, i, Cotinis nitida eggs, in 

 individual cavities but many eggs in a single ball of earth; a, b, and c much en- 

 larged, others about natural size. 



