Cimbex

Olivier, 1790

Elm sawflies, Birch sawflies, Almond leaf wasps

Species Guides

Cimbex americanus(elm sawfly)
Cimbex pacificus(Pacific Sawfly)
Cimbex rubidus(Rusty Willow Sawfly)

Cimbex is a of large, robust in the Cimbicidae, distributed across North America, Europe, and Asia. are among the largest sawflies, with body lengths reaching 20-25 mm, and are frequently mistaken for bees or due to their plump appearance and yellow-and-black coloration. The genus includes notable such as C. americanus (elm sawfly), C. femoratus (birch sawfly), and C. quadrimaculatus (almond leaf wasp), some of which are significant defoliators of trees. Larvae are caterpillar-like, with seven pairs of distinguishing them from lepidopteran caterpillars, and possess chemical defense glands. The genus has a fossil record extending from the Eocene to the Miocene.

Cimbex americanus by (c) Annika Lindqvist, some rights reserved (CC BY), uploaded by Annika Lindqvist. Used under a CC-BY license.

Cimbex rubidus by (c) Michael Warner, some rights reserved (CC BY), uploaded by Michael Warner. Used under a CC-BY license.

Cimbex rubidus by (c) Fue Her, some rights reserved (CC BY), uploaded by Fue Her. Used under a CC-BY license.

Pronunciation

How to pronounce Cimbex: //ˈkɪmbɛks//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

distinguished from other by large size, robust build, and clubbed . Resemble bees or but lack the constricted 'wasp waist' of Hymenoptera. Males with enlarged hind in some . Larvae identified by seven pairs of (/ caterpillars have five or fewer), coiled defensive posture when disturbed, rough pebbly texture, and black stripe. Cimbicidae antennae are clubbed and relatively short compared to other sawfly .

Images

Habitat

Deciduous forests, woodlands, and riparian areas with trees. Agricultural settings where host trees occur, including almond orchards (C. quadrimaculatus). Meadows adjacent to forest edges where engage in aerial interactions.

Distribution

North America (including United States, Canada, Alaska), Europe, and Asia. Fossil records from Eocene to Miocene in United States, Japan, and China. Specific distribution varies by : C. americanus widespread across North America from Atlantic to Rocky Mountains and Pacific coast; C. femoratus in Europe; C. quadrimaculatus in Turkey and parts of Asia.

Seasonality

active primarily in late spring and summer (May-July in North America). Larvae present from June through October, with some regional variation (e.g., May observations in South Carolina). One per year; larvae overwinter in cocoons and pupate the following spring.

Diet

Larvae feed on foliage of deciduous trees including elm (Ulmus), willow (Salix), birch (Betula), basswood/linden (Tilia), poplar (Populus), alder (Alnus), maple (Acer), and almond (Prunus amygdalus). feed on sap by stripping bark from twigs, sometimes girdling them; do not feed on pollen or nectar.

Host Associations

Prunus amygdalus (almond) - larval food plantC. quadrimaculatus
Ulmus (elm) - larval food plantC. americanus, primary
Salix (willow) - larval food plantC. americanus, frequently used
Betula (birch) - larval food plantC. femoratus, C. americanus occasionally
Tilia (basswood/linden) - larval food plantC. americanus occasionally
Populus (poplar) - larval food plantC. americanus occasionally
Alnus (alder) - larval food plantC. americanus occasionally
Acer (maple) - larval food plantC. americanus occasionally
Trichogramma minutum - C. americanus
Opheltes glaucopterus - larval C. americanus, C. quadrimaculatus
Phobetes nigriceps - larva-pupa C. quadrimaculatus, new record for Turkey and Asia
Listrognathus mactator - C. quadrimaculatus, new record for Turkey
Boettcheria cimbicis - pupal C. americanus, sarcophagid fly

Life Cycle

Complete with one per year. Females insert into leaves using saw-like ovipositor. Larvae feed on foliage, growing to approximately 43 mm, then crawl to ground and spin tough, papery cocoon in leaf litter or just below soil surface. Larvae overwinter in cocoons, pupating the following spring. emerge in late spring to summer.

Behavior

males engage in aerial duels and may defend territories, returning to perches after being disturbed. Larvae coil into defensive posture when disturbed; if further threatened, release volatile defensive chemicals from thoracic glands. Adults lack stinger despite intimidating appearance. Both sexes use strong to strip bark for sap feeding.

Ecological Role

Herbivore and defoliator of deciduous trees; rarely causes significant damage except in situations. Serves as for various and flies, contributing to dynamics. Pollination role minimal or absent.

Human Relevance

Occasional pest of shade trees, particularly elm, and agricultural pest of almonds in some regions. Rarely causes economically significant damage. Subject to programs in almond orchards. often provoke alarm due to large size and -like appearance, but pose no sting threat.

Similar Taxa

Trichiosoma (family Cimbicidae)Also large cimbicid with clubbed ; distinguished by different body proportions and larval associations
Other sawfly families (Tenthredinidae, Diprionidae)Smaller size, different structure (often thread-like or serrate rather than clubbed), different larval numbers or arrangements
Bees and wasps (Apidae, Vespidae)Convergent yellow-black coloration and robust build; distinguished by lack of constricted waist, clubbed , and wing venation in Cimbex
Lepidoptera caterpillarsSimilar larval appearance; distinguished by seven pairs of in Cimbex (vs. five or fewer in Lepidoptera), rough pebbly skin, and defensive coiling

Misconceptions

Despite and appearance, Cimbex are not bees or (though they are Hymenoptera), and cannot sting. The '' name refers to the saw-like ovipositor, not to any association with sawing wood. Larvae are often mistaken for caterpillars but are structurally distinct.