Supplementary Report on Insects Affecting the Straivberry. 255 



4. Topical applications may be either destructive or rcpellant, iiitendeil to 

 kill the insect or drive it away. The destructive agencies are either in the 

 nature of internal or external poisons, — killing by contact or by their action 

 after being taken into the alimentary canal. The internal poisons can rarely 

 be used except for the orders provided with masticatory mouths, which there- 

 fore bite and chew their food before swallowing it; and they are not usually 

 available against such insects as take their food by suction through a beak 

 or proboscis. 



Under the above system of classification of remedial and preventive meas- 

 ures, we may now arrange, for convenient reference, the modes of resistance 

 to the attacks of strawberry insects which have thus far been devised. 



1. Modes of Culture. 



la. Grass lands should sometimes be cultivated for two or three years in 

 some hoed crop, to expel the root-eating insects which devour not only the 

 roots of grass, but also those of strawberries. This measure is especially 

 recommended against the various white grubs. 



16. In the vicinity of towns where gas is manufactured, the lime used in 

 purifying the gas becomes saturated with sulphur, and accumulates as a 

 waste product, known as gas lime. In a fresh state this is destructive to both 

 vegetable and animal life, but on exposure to the air it is eventually con- 

 verted chiefly into the carbonate and sulphate of lime, both valuable fertil- 

 izers for many soils. 



The facts suggest the following procedure to free the soil from noxious in- 

 sects, preparatory to a change of crops. First treat the surface to a dressing 

 of fresh gas lime late in summer or early in autumn, and plow this under at 

 once, and then apply a second dressing of the lime to the plowed surface. As 

 the rain washes this into the soil, it will destroy the earth-inhabiting insects 

 both in that part of the soil turned over and for some distance benoath 

 The details of this procedure are still subjects for exi^eriment, and neither the 

 amount to be used, nor the length of time it is necessary to leave the fresh 

 lime in the ground before planting, have as yet been definitely ascertained. 

 The value of this application as a fertilizer will also vary according to the 

 character and history of the soil. 



Ic. Notwithstanding the utmost care against the invasions of noxious in- 

 sects, occasional rotation of crops will probably be necessary, in which case 

 the ground should ordinarily be plowed in mid-summer, after the picking of 

 the fruit. 



Id. In establishing a new plantation, it is best that the new plants should 

 be removed from the old field as early in spring as possible, as a safeguard 

 against the deposit of eggs upon them by noxious insects which may be hi- 

 bernating in the field and awaiting the opening spring for oviposition. Occasion- 

 ally it becomes necessary to take additional precautions against the transfer of 

 the eggs of injurious species from old lields to new. For this purpose the 



