502 EXPERIMENT STATION RECORD. 



The principal injuries to the roots are caused by the corn root aphis 

 {Apliis m<(diradici)i), the grass root louse {Schizoiieura panicola), white 

 grubs {Lach nosier na and CijclocephaJa spp.)? priouus grubs [Prionus 

 imbricornis and P. laticollis), Southern corn root worm {Diahrotica 12- 

 punctata), Northern corn root worm (D. longicornis), and wireworms. 



The life histories, natural enemies, and preventives and remedial 

 measures to be observed against these several insects are given in 

 considerable detail. 



Extensive studies are reported on the corn root aphis, white grubs, 

 the Southern corn root worm, and the IsTorthern corn root worm, these 

 insects having been especially investigated by the author. For the 

 economic procedure against the root aphis the following recommen- 

 dations are given : 



"Our present knowledge of eifective economic procedure for the corn root aphis 

 may be summarized in the form of the following recommendations: (1) That the 

 fertility of the ground should be maintained as a general safeguard, and that culti- 

 vation should be so managed, especially that of the lower parts of the lield, as to 

 l>revent so far as practicable the seeding of pigeon grass and smartweed among the 

 corn; (2) that infested iields should be plowed deeply and thoroughly harrowed late 

 in fall or during some suitable early winter interval; and (3) that a somewhat rapid 

 rotation of crops should be systematically followed, corn usually being allowed to 

 grow on the same ground but 2 years in succession. While some work remains to 

 be done with reference to the precise value of these methods in practical application, 

 there is no longer any doubt of their substantial usefulness, at least as a means of 

 holding in check the injuries of the corn root aphis." 



Direct remedies against the white grubs are given, but their eco- 

 nomic use seems rather improbable. Preventive measures by means 

 of fungus parasites, the value of which is not fully established, are 

 considered Avorthy further study. 



The life history of the Southern corn root worm is so little known 

 that preventive measures can not be given. It seems to be more 

 liable to attack sweet corn, and the proximity of cucurbits and the 

 other more common food plants of the beetle may account for its pres- , 

 ence. For the Northern corn root worm by rapid rotation and main- 

 taining a high degree of fertility the plant is able to withstand minor 

 injuries with relatively little loss. 



Report of the entomologist, M. H. Beckwith [Delaware Sta. Rpt. 

 ]895,pp. 160-175, figs. 5). — Notes are given of the San Jose scale and 

 other scale insects in Delaware, the imported elm leaf beetle, the use 

 of carbon bisulphid on cucurbits and for granary insects, arsenites for 

 the curculios and blister beetles, and poisoned baits for cutworms. 



The presence of the San Jose scale in DelaAvare was first noticed 

 in February, 1895, and it has since been observed in different sections 

 infesting pear, peach, ])lum, and crab apple trees. The life history and 

 means for the destruction of the insect are giren in considerable detail. 

 Brief notes are given on additional species of scale insects which have 

 been observed within the State, as follows: Oyster shell bark louse, 

 scurvy bark louse, rose scale, currant scale, and plum scale. 



