Reclinervellus nielseni is one of the spider-ectoparasitoids belonging to the Polysphincta genus-group (Hymenoptera, Ichneumonidae, Pimplinae) and utilizes exclusively Cyclosa spiders (Araneae, Araneidae) as hosts.

The species is distributed from Britain to Japan but is rather sparse.

Host spider species is different in accordance with the region, that is Cyclosa conica in Europe whereas Cyclosa argenteoalba in Japan.

Reclinervellus nielseni is known to manipulate web-building behavior of the host spider (Cyclosa argenteoalba) to modify an original fragile orb-web into a simple and durable web with conspicuous web decorations.

[3] Although the molting web structure usually only the two days the spider takes to molt, the larvae remain within their spider-cocoon for up to ten days before hatching.