Microplastics discovered in Caddy’s free casings since the 1970s suggest long-term contamination
The casing of the Ironoquia Dubia (RMNH.INS.1544419) was collected on May 18, 1971 in Lornen, Netherlands. Credit: Science of Total Environment (2025). doi: 10.1016/j.scitotenv.2025.178947
A team of biologists working at the Naturalis Biodiversity Center, a Dutch research museum, have discovered evidence of using Caddisisplastics with microplastics back to the 1970s.
In their study, a group reported in the journal Science of the Total Environment discovered microplastics in larval casings held at the museum.
Caddisfly is a moth-like insect found in most countries around the world. Insects build homes near lakes and streams where eggs are deposited into giant chunks of jelly. The larvae hatch after a few days and then immediately begin to wrap around the body to protect them from predators, using nearby materials.
In this new study, Dutch researchers discovered that starting more than 50 years ago, larvae began to include microplastics in their casings.
It started after one of the team members noticed something colorful in one of the larva casings held at the museum. When viewed well, it was shown to be microplastic particles. So the team looked into the 549 casings in the collection. In doing so, they found plastic in many of them.
As an example, the team found one casing with multiple particles of blue microplastics. This was dated in 1986. The other, with yellow plastic, was dated in 1971. Further studies of such casings showed that there was evidence of plastic additives such as lead, titanium and zinc.
Close-up of a casing of a Chaetopteryx villosa (rmnh.ins.1635762) collected in Austerland, Austerbeek on May 8, 1986. Credit: Science of Total Environment (2025). doi: 10.1016/j.scitotenv.2025.178947
Researchers suggest that microplastics have polluted the environment for at least the last half century, helping to explain how much they have been discovered worldwide. They also suggest that other species may be affected for equally long.
They conclude by stating that the plastic used in the casing is more visible than the natural substances used to construct the casing, and potentially potential factors that could potentially lead to the larvae being found and eaten by birds and fish.
Details: Auke-Florian Hiemstra et al, half-century Caddys-free casing (Tricoptera) with microplastics from the Natural History Collection, Total Environment of Science (2025). doi: 10.1016/j.scitotenv.2025.178947
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Quote: Microplastics discovered in Caddis Free Casings in the 1970s suggest long-term contamination (April 18, 2025) obtained from https://phys.org/news/2025-04-microplastics-caddisply-casings-1970s-htmll.html from April 19, 2025.
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