Zoologger is our weekly column highlighting extraordinary animals – and occasionally other organisms – from around the world

Skilled with a needle Niclas Fritzén

Species: Wasps of the genus Clistopyga

Habitat: Native to western Finland

Give a wasp a needle, and it’s only a matter of time until it starts to work with fabric.


Female wasps have a long, needle-like organ called an ovipositor which they use to pierce plant tissues or the exoskeletons of insects and deposit their eggs. But one group of parasitic wasps uses it not only for egg-laying, but also to make a type of felt with which to stitch up spider nests.

In 2015, Niclas Fritzén and Ilari Sääksjärvi of the University of Turku, Finland, ventured into the west of the country to track evasive Clistopyga wasps, which are poorly studied and easily confused with other wasps.

“This species is not easy to collect, and is impossible to study in nature,” says Fritzén. “They need to be collected and reared from the hosts [on which their eggs have been laid] in the lab.” Those hosts are a kind of jumping spider, which the wasps first paralyse using venom.

The team collected a single larva of the wasp on a paralysed adult jumping spider, along with small pieces of bark that contained spider nests.

They then offered spiders within their silken nests to the wasp and observed what happened. What they found surprised them. “I knew this was something new and very special,” says Fritzén.

The wasp inserts its ovipositor tip into the jumping spider, preventing it from escaping while the wasp injects the venom. It then reinserts the tip of it into the spider and drags the spider into a favourable egg-laying position.

Having laid its eggs, the wasp uses its ovipositor to poke at and pick up the spider silk of the nest, and closes openings in a zigzag stitching fashion. “The needle goes up and down like in a sewing machine,” says Fritzén.

The process is very similar to felting, in which needles grab the top layer of fibres and then enter the wool, tangling them with the inner layers. Here, the ovipositor acts as the felting needle, and the process makes the fluffy silk stiffer.

“The silken nest of the jumping spider is very soft and fluffy, because they consist of parallel layers of silk, apparently with a lot of air between,” says Fritzén. “Entangling these layers makes the silk more packed and stiffer, apparently also more durable.”

Why go to all this trouble? The team thinks it may be an adaptation that protects the wasp eggs against predation or parasitism. It also creates a stable microclimate inside the spiders’ nest, stops awakening spiders from escaping and prevents hatched wasp larvae from accidently leaving the nest.

“There is a growing interest in how biological systems can inspire nanotechnology in the textile world,” says Jeanette Lim, project manager at Ask Nature, an online catalogue of nature’s solutions to design challenges humans now face.

“Now that we’re learning more about what’s happening at the [tiny] scale in biological systems I think we’re then discovering how we can replicate what is going on, or how we can manipulate what’s going on so that it can serve us better in medicine or making textiles,” says Lim.

It could even lead to new types of felting needles.

“Although human needle felting and wasp egg-laying serve different purposes, it would be interesting to see if someone could create needles with recurved notches and find a use for them,” says Fritzén. Such needles might allow felt to be made more easily, without having to poke deep into the fabric.

Journal reference: Biology Letters, DOI: 10.1098/rsbl.2016.0350

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