Insects that construct shelters of willow leaves can be divided into two groups: species that use several leaves (tiers or bundlers), and species that use only one leaf (folders and rollers). Both of these informal groups include multiple species representing different insect groups, so species identification has to be done carefully in order to avoid making serious errors.

Leaf tiers

Willow leaf bundles made of multiple leaves are constructed by moths, sawflies, and beetles, and the bundles tend to look very similar although the construction method is different in each group. In all of these groups the aim of leaf tying is to provide shelter for the growing larvae.

Moth larvae

(Lepidoptera: Tortricidae, Yponomeutidae, and Noctuidae)

Leaves of willow shoots are tied together by larvae of numerous moth species belonging to several different families. Depending on the size of the larva, the shelter may consist of two or more leaves, but all lepidopteran leaf bundles contain a lot of silk webbing.


Leaf bundle constructed by an unidentified moth larva on Salix phylicifolia.


Brachycoluma sp.

(Hymenoptera: Tenthredinidae)

Shoot deformations caused by nematine sawflies in the genus Brachycoluma (= Decanematus) are superficially very similar to the shelters made by lepidopteran species. However, Brachycoluma bundles are created in a different way: while ovipositing, the sawfly females inject an unknown substance into the willow tissues. As a result, the leaves of the growing shoot become soft and sticky, and they are tightly glued together. Consequently, the deformed leaf bundles contain no silk webbing inside them. Like the lepidopteran tiers, Brachycoluma species occur on many willow species.


Brachycoluma sp. on Salix phylicifolia.

Brachycoluma sp. on Salix phylicifolia.

Byctiscus betulae

(Coleoptera: Attelabidae)

Leaf bundles of the polyphagous beetle Byctiscus betulae can usually be found on birch and aspen (right), but the species also attacks willows (left). As opposed to moth and sawfly larvae, B. betulae larvae do not have legs. The adults puncture or partially cut petioles and shoots in order to get the leaves together, which later leads to the drying of the leaf bundle.


Leaf shelter constructed by Byctiscus betulae on Salix caprea. Note the severed shoot and petiole, and the withering of the leaves.

Byctiscus betulae making leaf bundle on Populus tremula.

Leaf rollers and folders

Leaf rolls and folds on single willow leaves are made by many moth species, as well as by two different sawfly groups. Phyllocolpa sawfly rolls and folds contain none of the silk webbing which is present the rolls made by moths and pamphiliid sawflies.

Moth larvae

(Lepidoptera: several families)

Many moth species construct leaf rolls and folds on willows. Moth larvae tie the leaves with silk, so a lot of webbing is always present inside the shelters. The shape and construction method varies between moth species.


Small unidentified moth larva in the process of constructing a leaf roll on Salix phylicifolia.


Leaf roll made by a moth larva on Salix phylicifolia.


Leaf fold made by unidentified moth larva on Salix caprea. Note similarity to the Phyllocolpa folds below.

Moth larva in opened leaf fold on Salix caprea. Moth larvae are more flat-headed than sawfly larvae (see below), but the main difference is that moth folds have silk inside them.


Larva of another unidentified moth species inside leaf fold on Salix caprea.

Phyllocolpa species

(Hymenoptera: Tenthredinidae)

Leaf rolls and folds of Phyllocolpa sawflies are formed as a result of an abnormal growth response of the leaves, which is induced by the sawfly females during oviposition. Thus, Phyllocolpa shelters are compelely devoid of the silky threads that are always present inside similar-looking longitudinal rolls constructed by some moth larvae (see above). Click here to see more rolls and folds made by Phyllocolpa sawflies.


Leaf fold of Phyllocolpa leucosticta on Salix caprea. The larva also feeds outside the fold, but probably during the night.

Larva of Phyllocolpa leucosticta inside opened leaf fold on Salix caprea. Note the small pits and holes that the larvae of this species chew inside the fold.


Leaf roll of Phyllocolpa coriacea on Salix cinerea.

Leaf fold of Phyllocolpa sp. on Salix lapponum.

Pamphilius gyllenhali

(Hymenoptera: Pamphiliidae)

Pamphilius larvae make their rolls after cutting a slit across the leaf blade, so the roll is at a more or less oblique angle in relation to the leaf midrib. The roll is attached with thin silken threads, that are also present inside the shelter. Pamphiliid sawfly larvae have longish antennae and no abdominal prolegs.


Roll of Pamphilius gyllenhali on Salix caprea.

Pamphilius gyllenhali on Salix caprea. Note the silky threads that keep the roll in form.


Larva of Pamphilius gyllenhali taken out of a leaf roll on Salix caprea. Note the tiny legs, missing abdominal prolegs, and long antennae.

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