. Circular. Insect pests; Insect pests. MKTIIOl) OK INTRODUCTION, The suddenness and severity of the appearance of the Psylla, particularly in the .Maryland instances, makes the question of its introduction one of consider- able interest. Upon inquiry it was developed that in these cases the pear trees had been obtained from a New York nursery in is*)(), or just al the time when the Psylla appeared in such extraordinary numbers in New York State; and it is unquestionably from this source that the Psylla was introduced. The young trees secured in the fall of the year mentioned were undoubtedly
. Circular. Insect pests; Insect pests. MKTIIOl) OK INTRODUCTION, The suddenness and severity of the appearance of the Psylla, particularly in the .Maryland instances, makes the question of its introduction one of consider- able interest. Upon inquiry it was developed that in these cases the pear trees had been obtained from a New York nursery in is*)(), or just al the time when the Psylla appeared in such extraordinary numbers in New York State; and it is unquestionably from this source that the Psylla was introduced. The young trees secured in the fall of the year mentioned were undoubtedly infested with hibernating Psyllas, as it was in the immediate vicinity of the point where these trees were heeled in that the outbreaks occurred. In one case the insect seemed to have gradually increased in numbers, reaching a destructive abundance in the summer of 1894. The entire disappearance of the insect after the lirst year in the other orchard is probably to be explained on the ground of some local climatic condition. Such modifying influences are not unusual in the peach belt of Maryland, as illustrated by the fact that orchards separated by only a few miles, and with the same conditions as regards soil and variety of fruit, will seemingly be so differently affected by very local cold waves or storms that one will be barren while the other will be full of fruit. DESCRIPTION AND LIKE HISTORY. The Stages in the development- of this insect are the egg, the larva, the nymph or active pupa, and the adult or perfect, winged insect. The egg (fig. 2, a) is orange-yellow in color and so minute as to lie almost invisible to the naked eye. Its peculiar .-tincture is indicated in the drawing—the short arm serving as its attachment to the leaf. The newly hatched larva is somewhat larger than the egg and yellow in color, with crimson eyes, and has the characteristics indicated at fig. 2, //. With each of the earlier molts the form approaches more and more nearly the nymphal stage,
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Keywords: ., bookauth, bookcentury1800, bookdecade1890, booksubjectinsectpests
