When is the Willow Grub most available to trout?

January–March, typically 11:00–16:00. It picks up from about 14°C, peaks around 19°C and tails off by 25°C.

What flies imitate the Willow Grub?

Willow Grub, Tiny Yellow Grub, Caterpillar, CDC Grub, typically on a #18–16 hook.

How big is the Willow Grub?

Adult stage: 4–6mm. That matches a #18–16 hook.

Terrestrial · Terrestrial

Willow Grub

Euura proxima

Size

4–6mm

Hook size

#18–16

Hatch window

Season January–MarchPeak time 11:00–16:00

Water temperature

19° peak

14°25°

How fish feed on it

Nothing about a beetle or an ant belongs in the water, which is rather the point — once it's in, it isn't getting out, and a trout that's spent all summer learning this doesn't need convincing twice. The takes tend to be confident and unhurried, especially along undercut banks and under overhanging branches where windfall has been landing for as long as the tree's been there.

Flies that imitate this

Willow Grub

Tiny Yellow Grub

Caterpillar

CDC Grub

Ecology

Rivers & stillwaterFreestone rivers

Where you'll find this

New ZealandPresent

Present throughout

Identification

Euura proxima is a species of sawfly belonging to the family Tenthredinidae (common sawflies). The larvae feed on the leaves of willows ( Salix species) and was first described by Jean Guillaume Audinet-Serville in 1823.