Scaeva

Fabricius, 1805

Species Guides

Scaeva affinis(White-bowed Smoothwing)
Scaeva selenitica(Yellow-bowed Smoothwing)

Scaeva is a of hoverflies ( Syrphidae) comprising approximately seven described distributed across the Palaearctic region. The genus has been subject to taxonomic revision alongside related genera Simosyrphus and Ischiodon. are , while larvae are predominantly aphidophagous . Scaeva pyrastri has been extensively studied for its potential against agricultural pests.

Scaeva selenitica by (c) S. Rae, some rights reserved (CC BY). Used under a CC-BY license.

Scaeva affinis by (c) Rob Foster, some rights reserved (CC BY), uploaded by Rob Foster. Used under a CC-BY license.

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

Pronunciation

How to pronounce Scaeva: //ˈskee.və//

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

Identification

within Scaeva can be distinguished from related hoverfly by characters discussed in Láska et al. (2006). The genus is placed in tribe Syrphini based on morphological and molecular characteristics. Specific diagnostic features for the genus versus related are not detailed in available sources.

Images

Habitat

Orchard including litchi and guava; agricultural and natural environments supporting . Scaeva latimaculata has been recorded from litchi orchards in the Shivalik Hills, Himachal Pradesh, India.

Distribution

Palaearctic region broadly; specific records include Denmark, Norway, Sweden, and the Shivalik Hills of Himachal Pradesh, India. Distribution records from GBIF indicate presence in Scandinavia.

Diet

Larvae are aphidophagous; Scaeva pyrastri larvae feed on cabbage aphid (Brevicoryne brassicae). feed on nectar and pollen; Scaeva pyrastri adults have been observed consuming honeydew.

Host Associations

Brevicoryne brassicae - preycabbage aphid; primary prey for S. pyrastri larvae in laboratory studies

Life Cycle

For Scaeva pyrastri: total larval development 8.31 days; pre- stage 19.82 ± 0.25 days; adult female longevity 18.57 ± 0.37 days, male longevity 15.50 ± 0.17 days; pre-ovipositional period 4.25 ± 0.25 days, ovipositional period 8.50 ± 0.46 days, post-ovipositional period 3.25 ± 0.31 days; true time 28.86 ± 0.28 days; mean female 37.75 ± 1.16 . These parameters are derived from laboratory rearing on Brevicoryne brassicae.

Behavior

hover before landing on flowers. Scaeva pyrastri adults have been observed landing on lady beetles (Harmonia axyridis) to feed on honeydew accumulated on the 's from feeding. Larvae are active of aphids.

Ecological Role

Larvae function as agents of ; serve as of various crops. In orchard , syrphids including Scaeva contribute to pollination services during bloom periods.

Human Relevance

Scaeva pyrastri has been evaluated for of cabbage aphid in agricultural systems. contribute to crop pollination. The is not known to be a pest or .

Similar Taxa

SimosyrphusClosely related ; taxonomic boundaries between Scaeva and Simosyrphus have been discussed by Láska et al. (2006)
IschiodonClosely related ; included in taxonomic revision alongside Scaeva by Láska et al. (2006)
EristalisBoth are hoverfly in Eristalinae versus Syrphinae; Eristalini members dominated litchi orchards while Syrphini (including Scaeva) showed different distribution patterns in comparative studies

More Details

Taxonomic note

The of Scaeva and related Simosyrphus and Ischiodon was revised by Láska et al. (2006), clarifying relationships within Syrphini.

Research context

Most detailed biological information available for the derives from laboratory studies of Scaeva pyrastri; field efficacy and natural history of other remain poorly documented.