As they already said, yes, high grade ethanol (96%-99.9%) is perfect if you want to preserve your sample for DNA extractions! I would recommend to keep the samples preserved in Ethanol either in a fridge or a freezer. Moreover, if you could keep the insect in vials (e. g. Glass tubes) that are completely submerged in a bigger vial (such as a jar) that is full of ethanol too, it would avoid EtOH evaporation! Sometimes you can extract DNA even after 20 years, the important is to avoid evaporation and the consequent drying of the samples.

Hi,

You can read this paper for more conservation methods:

Article Evidence-based recommendations on storing and handling speci...