332 REPORT OF STATE BOARD OF HORTICULTURE. 



flying- forms that will spread to parts of his orchard not previously infested. 



In my own experience tobacco has given as good a result as any other 

 material applied, and, combined with fish-oil soap, it comes as close to being 

 a perfect remedy as it is easy to get. The trees at this early period of their 

 growth will stand almost any reasonable application without injury, and two 

 drenchings with either of the materials suggested, at the strength men- 

 tioned, may be safely given. It is important to remember that all these 

 contact poisons kill only that which they actually touch ; hence every appli- 

 cation should be iiO made as to touch, if possible, every part of the treated 

 tree. It is not possible to do this in all cases ; but it can be done in so large 

 a percentage of instances that the results will be satisfactory. 



If trees become infested during the summer, they should be thoroughly 

 sprayed with a somewhat stronger mixture late in September — say the 

 twenty-fifth, and again in early October — say the fifth. This will kill the 

 immature males and females, and will prevent oviposition. 



The spraying mixtures used at this late season should be at least one- 

 fourth stronger than those recommended for spring work, because of the 

 greater resisting powers of the parthenogenetic females, which are at that 

 time bearing the sexed forms. It goes without saying that thoroughness is 

 as important at this time as at any other, and that no insects are killed other 

 than those actually hit by the spraying mixture. 



Crude petroleum is not recommended as against these insects at any time. 

 Winter applications will fail to be effective against the eggs, which resist 

 even undiluted kerosene in ordinary applications. Fumigation with hydro- 

 cyanic acid ^as is said to kill the eggs, and this method will check the dis- 

 tribution of the species on nursery stock. 



Trees known to be well stocked with eggs should be closely trimmed dur- 

 ing the winter and the cuttings burnt. As the eggs are preferably laid near 

 the tips, this method will destroy a large proportion of them. The modern 

 method of cutting back to a single stick, trees just set out, is in line with the 

 recommendation just made and renders the destruction of the insects easy 

 for two years ; but the cuttings must be at least removed from the orchard 

 and preferably should be burnt, to prevent the young lice, when hatched 

 from the eggs on the cut twugs, from crawling to the growing trees. 



METHODS OF DISTRIBUTION. 



The normal or natural method for the spread of this insect is by the flight 

 of the winged form from the trees where they hatched, to others. New 

 orchards in somewhat isolated locations would then be comparatively free 

 were it not for the fact that nurseries are generally infested by this insect. 

 The eggs are therefore distributed with the young stock, and new planta- 

 tions are infested from the very start, when least able to resist attack. 

 Young trees can be very easily cleaned, however, and this is a point to 

 which the orchardist should look if the stock has not been carefully fumi- 

 gated before it was sent out. 



Note — All the figures illustrating this bulletin are original. The drawings were 

 made with the camera lucida and the lack of symmetry in the pictures is due to the fact 

 that I preferred to show the specimen just as it appeared on the slide. 



