Old DNA can be a great tool for studying evolution, diversity and other subjects, but getting hold of the stuff can be tricky. When the old organisms are small insects, retrieving a bit of DNA can mean destroying all or parts of them.

Now a team of scientists has shown that it’s possible to extract DNA from nearly 200-year-old insect specimens without ruining them. They give the bugs a good soak.

Eske Willerslev and Philip Francis Thomsen of the University of Copenhagen and colleagues used a solution called a digestion buffer, the recipe for which had been previously developed. Twenty museum beetle specimens dating from as far back as 1820 were immersed in the solution for about 16 hours, then removed and dried, their exoskeletons and other features intact. Nucleic acids in the remaining solution were purified.

In a paper in the online open-access journal PLoS ONE, the researchers report that all 20 specimens produced usable mitochondrial DNA sequences. It’s thought that the digestion buffer gets inside the exoskeletons through the mouth, respiratory holes and other anatomical features, and through holes made when the specimens were pinned for display.