306 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. 



them, cleaning their roots, cutting out any nodosities if need be, and 

 immersing the roots in a petroleum (kerosene) bath consisting of 

 2-^ lb. of soft soap, 9 gallons of petroleum, and 90 gallons of rain 

 water. 



Coccides. — In spite of the thick shell which protects the coccides, 

 they may be overcome by petroleum and its emulsions » when they live 

 in the open. Petroleum is one of the rare substances which really act on 

 coccides. In the pure state its action is radical. It is recommended 

 in that state when it is a case of a dangerous invasion which must be 

 stopped by the complete destruction of the parasite. "When cochineals 

 such as Aspidiotus perniciosus, Comst. (San Jos6 louse), Aspidiotus 

 ostreaformis, Curtis (pear-tree oyster scale), an American coccide 

 the appearance of which was first reported in France in 1892, 

 Mytilaspis pomorum, Hook (apple-tree mussel scale), Diaspis piricola 

 (pear cochineal), and others — when these make their first appearance 

 in an orchard, pure petroleum must be used, taking the precautions 

 previously described — precautions which are indispensable to pre- 

 serve the tree in good health and circumscribe the plague. In most 

 cases emulsions may suffice, and where the dangerous coccides are in 

 the endemic condition, as in America, regular annual treatment with 

 dilute emulsions prevents their too great multiplication in orchards 

 without completely destroying them. It is the same with the coccides 

 as with the phylloxera. There is an extinction treatment when 

 this insect makes its first appearance, and a cultural treatment where 

 it lives in the endemic state and where it suffices to create a models 

 vivendi between the tree and its parasite. Cultural treatment is 

 effected with dilute solutions, especially if the moment chosen for 

 treatment be that when the young delicate larvaB emerge from the 

 protective carapace of their mother, where they have been sheltered 

 during the first days of their larval evolution. At that time they are 

 as sensitive as the aphides and succumb to 2-5 per cent emulsions 

 (Fleischer) or 6-6 per cent (Kruger), which no longer injure the tree. 

 The adult females covered by their carapace are more resistant. In 

 winter, 25-30 per cent emulsions must be used against Aspidiotus, 

 12-15 per cent against Lecanium nigrofasciatum (kermes of the peach, 

 Johnson), 5-10 per cent against kermes of the lemon-tree. It is well 

 to give several treatments, at eight or fifteen days' interval, as advised 

 by Belle, and to follow this winter treatment by a spring treatment 

 with a weak emulsion intended to destroy the active larvae. In this way 

 the treatment is complete and without injury to the fruit tree. Belle 

 •advises this treatment( to destroy Clirysomphalus 7ninor (orange 

 ■cochineal), Targioni-Tozzetti to destroy Pidvinaria vitis, L. (vine 

 oochineal), and Marchal to overcome Guerinia serratulcB, Fab. (kermes 

 of the pine, cypress, and acacia). Petroleum and its emulsions applied 

 judiciously are capable of easily destroying the coccides. 



Use against Diptera. — Psila Bosce, Fabr. (carrot fly) ; AntJio- 

 myia Brassicce, Bouche (turnip fly). — Schoyen recommends 12 per 

 cent emulsions to overcome these flies which do great damage. 



Use against Acari. — TetranycJius telarius (red spider). — Kolbe 

 advises the use of an emulsion of 1 per cent of petroleum and 1 per 



