GB: Bean-caper Hawkmoth, D: Doppelblattschwärmer, RU: Parnolistnikovyi Brazhnik, E: esfinge del frijol de las alcaparrasSphinx zygophylli Ochsenheimer, 1808, Schmetterlinge Europa 2: 226.
Type locality: Southern Russia [Turkestan].
(Taxonomic note. In such a variable species, especially one which responds to local climatic conditions, the creation of separate taxa for pale individuals from the former Soviet Turkestan and Mongolia cannot be justified.)
Holarctic; western Palaearctic region. Pleistocene refuge: Polycentric -- Turanoeremic and Mongoloeremic refugia.
Wingspan: 60--75mm. Forewing yellowish brown with a narrow, yellowish white, median stripe running from base of inner margin to apex, from which one or two branches extend towards costa; wing margin yellowish. Forewing much narrower than in related species. Similar to some forms of Hyles livornica (Esper, 1780). Variable in both colour intensity and size of markings; specimens from drier areas tend to be paler, with more yellow coloration.
Occurs on hot alkaline flats, sand-dunes and arid hillsides where Zygophyllum fabago (Syrian bean-caper) grows, as well as sparse riverine scrub in more arid areas.
End of April to mid-May, July/August and sometimes mid-September in two or three generations. In cooler mountainous areas, most are to be found during June/July, with a partial second generation in late September/October.
OVUM: Size unrecorded but larger than most species of Hyles, spherical, bright green; very similar to that of Laothoe populi (Linnaeus, 1758). Laid on the underside of a leaf, hatching from two to five days later.
LARVA: Full-fed, 70--80mm. Polymorphic. Fully grown, primarily pale green or yellow, with a black reticulate pattern dorsally and laterally; ventro-lateral and lateral surface unmarked. A narrow yellow dorso-lateral band with small black-ringed yellow or white eye-spots of variable size. In some the head, dorsal line, horn and anal claspers are black; in others they are yellow or pale green. All forms have a yellow band beneath the orange or white spiracles.
On hatching, the larva takes up a position along the midrib on the lower surface of the leaf. During later stages, most feed fully exposed, clinging to a stem while avidly consuming leaves and flowers. From egg to pupa takes approximately 30 days.
Common between May and September, sometimes later in hot localities. Mitroshina (1989) recorded densities of 83.3 larvae per 100 hostplants examined for northern Turkmenistan.
Major Hostplants. Usually Zygophyllum fabago. Other species of Zygophyllum are utilized locally, such as Zygophyllum oxianum (Mitroshina, 1989) and Zygophyllum eichwaldii.
Minor Hostplants. Possibly the flower-heads of Eremurus. Tribulus will be accepted as an alternative hostplant by most captive larvae, and may thus also be a wild host.
PUPA: 40--50mm. Light, sandy brown, with fine dark lines. In summer, this stage lasts no more than eighteen days. Overwinters as a pupa.
Western Turkey (Danner, Eitschberger & Surholt, 1998), central and eastern Turkey (de Freina, 1979; de Freina, 2012), northern Syria, the Republic of Georgia (Didmanidze, Petrov & Zolotuhin, 2013), Armenia (Didmanidze, Petrov & Zolotuhin, 2013; Wąsala & Zamorski, 2015) and Azerbaijan (Didmanidze, Petrov & Zolotuhin, 2013), Daghestan (Abdurahmanov, 1999), the lower Volga valley of Russia, eastern Transcaucasia (with its main stronghold in the low-lying areas around the Caspian Sea (Eversmann, 1844)), northern Iran (Danner, Eitschberger & Surholt, 1998), Turkmenistan, most of Kazakhstan (Shovkoon, 2015), Uzbekistan (Kondratiev coll., NHMUK), Kyrgyzstan (Eitschberger & Lukhtanov, 1996; Korb, 2018), Tajikistan (Grum-Grshimailo, 1890), northern Afghanistan (Ebert, 1969), and western Xinjiang Province, China (Pittaway & Kitching, 2000).
There is one record of a vagrant from Croatia (a specimen in the Carnegie Museum, labelled 'Dalmatia' (Ian Kitching, pers. comm. 2005)). Via vagrants, this species may colonize Romania in the future, where Zygophyllum fabago has become quite widespread (König, 2003).
Extra-limital range. Northern and central Xinjiang Province, China (Pittaway & Kitching, 2000) east to Shaanxi Province (Eitschberger, 1999), and north to Mongolia (Derzhavets, 1977; Saldaitis & Ivinskis, 2006) and the Selenga River valley, Buryatia, Russia (Pascal Régnier, pers. comm. 2012).