73 THE EEPOET OF THE No. 36 



and pierced the pears till they were bathed in the sap that oozed from the punc- 

 tures. In the laboratory, adults have left a fairly ripe, soft apple to feed upon a 

 hard green pear. All through the season a favorite place for the bugs to feed is 

 about clusters of apples that have been dwarfed by the Eosy Aphis, and here the 

 adults can be found, when nowhere else, late in the season. These belated individuals" 

 also show a preference for over-ripe or even decaying fruit. 



'Chabacter and Extent of Injury. 



1. Injury to the Apple. — The first evidence of injury is to the tender foliage 

 in the form of purplish spots upon tlie surface of the leaf, accompanied, in severe 

 cases, by a slight tendency to curl. To one who is familiar with the work of this 

 insect, this symptom is most characteristic and makes it possible to detect the pre- 

 sence of the nymphs at a very early stage, and even when they are present in small 

 numbers. Six newly hatched nymphs were placed on an apple seedling in the 

 laboratory, and twenty-four hours later every leaf was spotted with the typical 

 purplish markings. As the leaves unfold and later reach full size, the discoloration 

 disappears, -but if affected leaves are held up to the light they will appear to he 

 pierced through and through with tiny holes. Very severe attacks result in a 

 ragged, frayed appearance of the leaf. By these symptoms, the former presence of 

 the bugs on any tree can be detected long after they have completed their trans- 

 formation and disappeared. 



The tender, succulent twigs are also subject to attack, and as the insect with- 

 draws its beak a drop of clear or amber sap oozes through the bark, marking the 

 puncture. Later, as the twig increases in size, quite a decided lump may develop 

 at the point of puncture, accompanied in severe cases by a longitudinal crack. 



Ill heavily infested orchards, where the insect may be present in tens of 

 thousands, the repeated puncturing and withdrawing of the sap goes so far that 

 affected twigs wilt, the leaves become brown and dry, and finally the whole shoot 

 dies. Cases where many of the twigs were literally stung to death in this way were 

 quite common early in the summer. Later the dead twigs dropped off and were 

 replaced by a strong new growth, which covered up the injury done by the bugs. 



As the blossom petals appear and begin to unfold they are quickly attacked 

 by the young nymphs, which have been frequently observed right inside a blossom 

 with beak inserted in the pistil. In fact, so numerous were the insects and so per- 

 sistent their attacks that the blossoms and the blossom pedicels wither and die, 

 having been sucked quite dry by the nymphs. These dead and dry blossoms remain 

 on the tree for some time, but break off and fall to the ground before the end of 

 the season. These facts explain why susceptible varieties may come into bloom year 

 after year but never set a crop of fruit. 



As soon as the young fruit is formed, drops of gum oozing through the skin 

 show that it also has been punctured by the insect. Later, slightly raised, dis- 

 colored spots mark the injury, and a large proportion of fruit so injured drops to 

 the ground in the course of a few days. Apples that are able to cling to the 

 tree or that remain uninjured until later on in their life, are badly gnarled and 

 misshapen as a result of the insect's attack. The tissue above the puncture 

 fails to develop and, as a result of the uneven growth, the apple will be one-sided 

 with a pronounced depression about the point of puncture, which itself is marked 

 by a brown, corky scar with ruptured epidermis. 



2. Injury to Pears. — Injury to the leaves, stems and blossoms of the pear 

 resembles that of apple, except that in this case the tissue about the puncture 



