The curculio is a native of North America and for more than 150 years has been known as an enemy of fruits. Our early horticultural literature abounds with reference to its depredations. In more recent times the great increase in planting of fruits, brought about to supply the increased demand, has permitted it to become much more abundant than formerly, and the plum curculio constitutes at the present time one of the most serious insect enemies of orchard fruits. Statistics gathered of its depredations show that it is distributed over much of the area of the United States. Its western limit is, roughly, a line drawn through the centers of North Dakota, South Dakota, Nebraska, Kansas, Oklahoma and Texas. East of this line the entire United States is infested except the southern third of Florida and the northern half of Maine.
Is the plum curculio causing much damage to the fruit growing industry of this country? That it is is shown by the National Conservation Committee in its report in Volume III, page 309, where it states that the average annual loss in late years to only three fruits is as follows:
| Apples | $3,257,806 |
| Peaches | 4,088,814 |
| Plums | 1,244,149 |
| ————— | |
| Grand Total | $8,590,769 |
Just think of it! A total loss each year to only three fruits of over $8,500,000. This amount is a heavy drain upon the fruit growing industry of this country. During the past twenty-five or thirty years the total damage caused by this insect, to the various fruits which it attacks, would, on a conservative estimate, probably be not less than $100,000,000.
These figures show the absolute need of the adoption of effective remedial measures against this insect so as to lessen this loss. But before we can hope to combat this insect systematically and successfully it is necessary to know its life history and habits.
The curculio in its stages of growth, and its fruit injury.
There are four distinct stages in its life cycle: (1) The egg, (2) the larva, or "worm," (3) the pupa, and (4) the adult, or beetle.
The curculio passes the winter in the adult stage under accumulations of partly decayed leaves, among the closely-packed dried grass of sod-covered orchards, and probably wherever suitable protection from the winter may be found. Its depredations are usually worse near woods, so it probably finds here very suitable places for wintering.
In the spring, when the fruit buds are unfolding, the beetles begin to emerge from their winter quarters and feed to some extent on the blossoms and tender leaves of the fruit trees. Mating soon begins, and by the time the fruit is well set the beetles make this fruit the chief object of their attention. The circular punctures in the skin are feeding punctures, while the crescent-shaped ones are egg-laying punctures. A single egg is deposited in a puncture, although several may be placed in a single fruit. From one to eight eggs may be deposited daily by an individual female, which may be continued for several months. The great majority of the eggs, however, are deposited by the end of eight weeks. These eggs hatch in from three to seven days, being influenced greatly by the weather.