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Croesus septentrionalis

Birch sawfly

Description

The approx. 10 mm long wasps fly in May/June and possibly in a further generation in August. The eggs are inserted in the leaf veins. Upon hatching the larvae feed gregariously along the leaf edges. When disturbed, all members of a colony synchronously raise their abdomens in a flash and take on an S-shaped defence pose. Fully grown 25 mm long larvae enter the soil for pupation. Second generation larvae can be found as late as early October. They then overwinter in the soil and pupate the following spring. At high infestations smaller trees are completely defoliated, and only the leaf veins remain. This may not be desirable in ornamental shrubs and trees. I occurs in forest edges, parks and, gardens.

Symptom

At high infestations smaller trees are completely defoliated, and only the leaf veins remain. 

Tree Species: Birch

Part of a plant- attacked: Leaf / Needle

Pest significance: Less harmful

Pest Category: Insects

Invasive Species: No

Present in EU: Yes

Last observations

There are a total of 2 observations of the species in the system

Croesus septentrionalisBirch sawfly
Mario Rolak
Number of votes: 0
Published: 5.8.2018

Croesus septentrionalisBirch sawfly
Mario Rolak
Number of votes: 0
Published: 5.8.2018

Croesus septentrionalisBirch sawfly
Milka Kováčiková
Number of votes: 0
Published: 15.6.2018