Provided is a sustained release preparation comprising an insect pest-targeting gel composition, the preparation being free from leakage or reaction of a volatile substance and being capable of releasing the volatile substance at a constant rate. More specifically, provided is a sustained release preparation including a polymer tube having a sharp end and an insect pest-targeting gel composition in the polymer tube, the composition including one or more volatile substances and an oil gelling agent, wherein the volatile substances are included in an amount of from 70.0 to 99.0% by weight by the insect pest-targeting composition and are released outside of the polymer tube through the polymer tube.
