To establish an efficient method for preservation of field-collected beetles for molecular genetic analyses, 5 different preservation treatments were compared: ethyl acetate,ethanol, Camoy fixative, DNA isolation buffer, and liquid nitrogen. Cryopreservation by immersion in liquid nitrogen and subsequent storage at −80°C was found to be the best method for long-term storage. Storage in ethanol at room temperature preserved the DNA for ≍6 wk. Storage in DNA isolation buffer was also effective but required the insects to be thoroughly homogenized to produce intact DNA, which destroyed insect morphology. Ethyl acetate and Camoy fixative did not preserve the DNA. Preservation in ethanol was the easiest method, because it neither required grinding of insects nor transportation and maintenance of special equipment, such as a dewar flask for liquid nitrogen. However, because the DNA was found to degrade after ≍6 wk, ethanol was useful only for short-term storage.