Scientists were able to sequence DNA of insects that had crossed a black widow spider's web by sampling the web itself.

These new method could have practical applications in conservation research, the Public Library of Science reported. The technique could also be used in fields such as "pest management, biogeography studies, and biodiversity assessments."

"Noninvasive genetic sampling enables biomonitoring without the need to directly observe or disturb target organisms," the researchers stated.

In this study the researchers used three black widow spiders that were fed house crickets to extract and sequence DNA from the web samples. The method allowed them to identify both the type of spiders that made the webs and the type of prey they had captured.

As dominant predators of arthropod communities in natural and agricultural ecosystems, spider are important ecological indicators that reflect habitat quality and change across trophic levels. Monitoring the species diversity and abundance of spider 32 assemblages facilitates natural resource management," the researchers wrote in their study.

The researchers noted the detectability of spider DNA did not differ between assays. The team found the spider and prey DNA remained detectable at least 88 days after the web had been abandoned. This means scientists could determine which spiders and prey had inhabited a spider web, even if both species had perished or left the web months before.

"Sticky spider webs are natural DNA samplers, trapping nearby insects and other things blowing in the wind. We see potential for broad environmental monitoring because spiders build webs in so many places," said researcher Charles Cong Xu.

The findings were published in a recent edition of the journal PLoS ONE.