The Strawberry Weevil.

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As strawberries are about to blossom, it would be well to keep a look-out for a shortage in the number of blossoms, for this is the first indication of the work of the strawberry weevil. Because of the diminutive size of the insect, few are acquainted with it, so that the shortage of blossoms or failure of the crop is often attributed to frost, hail, climatic conditions or some other agency. Upon close examination, the buds will be found to be severed from the stem, some lying beneath on the ground, others being still attached by a few shreds in a drooping manner. Further examination around the buds may reveal a small snout beetle, which is the cause of the injury, it being about one-tenth inch long and marked with two dark spots on each wing cover. The females oviposit in the buds, and then cut them off when oviposition is completed, in order to protect the larva within, which later develops to the adult beetle.

Showing beetle of strawberry weevil and the damage it inflicts. Showing beetle of strawberry weevil and the damage it inflicts.

The strawberry weevil has been especially injurious around the vicinity of Hopkins the past summer. It was not uncommon to find fields with from forty to ninety per cent. of the buds cut, and as the earliest and most mature buds, which would be the first to ripen, are among those cut, the losses inflicted may be quite serious. The weevil not only injures the cultivated strawberry, but is found to attack the buds of the red raspberry, dewberry and wild strawberry. It is a singular fact that only the staminate varieties are injured, especially those which furnish considerable pollen, since this constitutes the chief food supply of both larvae and adults.

Life History.—The weevil appears as soon as the buds begin to form and soon after deposits an egg within the bud. She then immediately crawls down the stem and proceeds to sever the bud. The eggs hatch within five or six days, and in about three or four weeks the footless grubs become full-grown, coming out as adults about five days later. This new brood, upon emerging, will attack the leaves, making numerous small holes on the under surface, soon after picking time. As early as August 25 the beetles were found to go into hibernation last summer, within the strawberry fields, being found especially among the dead leaves. The older beds were found to be more seriously infested because of the fact that they wintered over in the small fields.

Control.—Since the weevils do not disperse readily, and since they hibernate within the fields, the one crop system and the plowing up of the beds immediately after picking would probably do away with the injury entirely. This one crop system could be followed for about two years, when it might be advisable to return to the two crop system if the weevils have disappeared.

On April 18, 1916, the weevils were located by the writer underneath the straw, and beginning to move about. From observations last year, it would be advisable to remove the straw from one or two rows in order to hasten the maturity of the buds, and keep the straw on the remainder of the patch in order to force the weevils to the uncovered row. They could then be destroyed either by plowing under or burning.

Some recent experiments by Prof. Headlee, State Entomologist of New Jersey, appear to have been successful against the strawberry weevil. A dust spray of a mixture of arsenate of lead one pound, and sulphur one pound, was used as a repellent, giving almost perfect protection. The material was applied twice, April 30th and May 6th.

The writer will be glad to co-operate with the growers, if they find the presence of the weevil in their strawberry beds.—S. Marcovitch, Section of Economic Entomology, Division of Economic Zoology, University Farm.


                                                                                                                                                                                                                                                                                                           

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