Euxoa declarata

Walker, 1865

clear dart

Euxoa declarata is a commonly known as the clear dart. have a wingspan of 31–37 mm and are active from July to September with one per year. The is notable for its reproductive isolation from closely related species (E. campestris and E. rockburnei), which is maintained primarily through differences in circadian mating rather than differences. Males of all three species respond to the same synthetic . The species belongs to the 'declarata group' of Euxoa, a complex of interfertile that remain reproductively isolated in nature through temporal partitioning of mating activity.

CATALOGUE-BM-LXV by Sir GEORGE F. HAMPSON, Bart.. Used under a Public domain license.

Euxoa sp. (29260587803) by Donald Hobern from Copenhagen, Denmark. Used under a CC BY 2.0 license.

Pronunciation

How to pronounce Euxoa declarata: /juːkˈsoʊ.ə dɪˈklær.ə.tə/

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Identification

Wingspan 31–37 mm. Distinguished from E. campestris and E. rockburnei by differences in female calling posture at 20°C (becomes indistinguishable at lower temperatures). Most reliably separated from by temporal activity patterns rather than morphological features.

Images

Habitat

preferences appear to differ slightly from closely related E. campestris and E. rockburnei, contributing to reproductive isolation in nature. Specific habitat details not documented in available sources.

Distribution

Canada: Ontario, Quebec, New Brunswick, Nova Scotia, Prince Edward Island, British Columbia, Alberta, Saskatchewan, Yukon, Manitoba. United States: Minnesota, North Carolina, Arizona, New Mexico, California. Western limit: central Alaska.

Seasonality

active July to September. One per year.

Behavior

. Female calling ( release) occurs during scotophase, with timing temperature-dependent—calling occurs progressively earlier as temperature decreases from 20°C to 5°C. At 20°C, exhibits distinct calling posture compared to ; posture becomes indistinguishable at lower temperatures. Reproductive isolation from E. campestris and E. rockburnei maintained primarily through -specific of mating activity.

Similar Taxa

Euxoa campestris in the declarata group; interfertile but reproductively isolated in nature by temporal partitioning of mating activity. No cross-attractancy under natural , though cross-attraction can be induced by photoperiod manipulation.
Euxoa rockburnei in the declarata group; parapatric distribution with some cross-attractancy to E. campestris but not to E. declarata under natural conditions. Reproductive isolation maintained primarily by differences in mating .