This is a fairly large species (19–30 mm) that is rather recognisable having relatively narrow dark brown forewings. The abdomen has yellow bands on all segments but those closer to the thorax are narrower than those towards the end of the abdomen.
The antennae are strongly feathered (pectinate) in the male. The proboscis is reduced and non-functional.
The males are strongly attracted to the pheromone synthesised for this species, and are best lured in the afternoon although the optimal time span is very weather dependent.

The female deposits the eggs at the underside of the leaves of the foodplant close to the leaf edge. They are mostly laid singly or with two together, but never in a cluster.

The larva is off-white, as in all clearwings.

The caterpillar makes galleries in the rootstock and in a stem of its host. In this stem, the future exit hole is constructed too.

The pupa can move freely in its gallery as there is no cocoon.

When the young larva hatches from the egg, it moves down towards the root of the plant and feeds in the base of a stem, eventually causing a typical swelling. It subsequently moves into the rootstock and hibernates there. In springtime, the larva continues to feed in the rootstock and starts during that year to gnaw a gallery in a stem. After a second hibernation, the larva gradually completes that shaft and constructs during the summer also the future exit hole at the end of this gallery.
The larva pupates without making a cocoon allowing the pupa to move freely inside the gallery.

The larva bores into the rootstock and the lower parts of the stems of Rubus idaeus (raspberry). Only occasionally also Rubus fruticosus (blackberry) is taken as a host.

P. hylaeiformis occurs everywhere where the hostplant grows: forest edges, clearings, roadsides, gardens, ...