LAOTHOE AMURENSIS (Staudinger, 1892)

GB: Aspen Hawkmoth, F: Sphinx du Tremble, D: Zitterpappelschwärmer, Espenschwärmer, RU: Osinovyi Brazhnik, S: Asp-Nattsvärmare, PL: Zawisak osinowiec, FI: Haapakiitäjä.

Smerinthus tremulae var. amurensis Staudinger, 1892, in Romanoff (ed.), Mém. Lépid. 6: 232.

Type locality: [Russia, Khabarovsk Kray/Primorskiy Kray,] Ussuri.

(Taxonomic notes. (i) This species is often referred to as Laothoe tremulae. However, as Sphinx tremulae Boisduval is a junior primary homonym of Sphinx tremulae Borkhausen, 1793 (see Laothoe populi populi (Linnaeus, 1758)), the next oldest available name must be used.

(ii) Subsp. baltica Viidalepp, 1979, is not tenable as it is clearly only a form that appears occasionally within the European range of the nominate subspecies. However, Zolotuhin (pers. comm.) disputes this and states that all western Palaearctic material should be referred to as subsp. baltica.

(iii) Laothoe sinica (Rothschild & Jordan, 1903), which is usually treated as a subspecies of Laothoe amurensis, and found in central China from Jilin Province to the foothills of the Tibetan plateau and Yunnan Province, appears to be a distinct species allied to Laothoe amurensis. Notable localities are the Daba (Tapa) Shan and Qinling (Tsinling) Shan ranges south of Xi'an. Chu & Wang (1980b) also record Laothoe sinica from western China, but this is probably erroneous.)


BIOGEOGRAPHICAL AFFILIATION

Holarctic; Palaearctic (both eastern and western). Pleistocene refuge: Monocentric -- Manchurian refuge.


ADULT DESCRIPTION AND VARIATION

Laothoe amurensis amurensis (female above, male below).

Wingspan: 75--95mm. Closely resembles Laothoe populi populi, but immediately distinguishable by the absence of the rust-red patch at base of hindwing, although there may be a tint of brown present in some individuals. Ground colour equally variable, ranging from buff through pink to various shades of grey. The small, dark-grey form is referable to f. baltica Viidalepp. According to Rothschild & Jordan (1903), in the male genitalia, the sacculus is much broader than in Laothoe populi populi, the two lobes (processes) being very broad; the aedeagus is multispinose around almost all the edge, with the spines being small on one side; uncus shorter than in Laothoe populi populi, gnathos more evenly convex below, its sides straighter, the apex more obtuse.


Male Laothoe amurensis amurensis f. baltica, Plunge District Municipality, Telsiai County, Lithuania, 22.v.2011. Photo: © Darius Bau×ys. Female Laothoe amurensis amurensis, Siberia, Russia. Photo: © Mark Boddington Male Laothoe amurensis amurensis (pale form), Omsk, Siberia, Russia. Photo: © Frank Deschandol Male Laothoe amurensis amurensis (pale form), Omsk, Siberia, Russia. Photo: © Tony Pittaway.

ADULT BIOLOGY

This species is found in woodland clearings and on lake margins abounding in Populus tremula (aspen); rarely elsewhere.

The behaviour of Laothoe amurensis amurensis is very similar to that of Laothoe populi populi. It rarely flies before midnight and has often been seen to fly to and fro over still water, dipping into it repeatedly (Skvortsov & Thomson, 1974). Certain tropical sphingids such as species of Pachylia Walker, Hemeroplanes Hübner and Perigonia Herrich-Schäffer are known to drink and this species may do the same. Individuals in any one population tend to emerge within 5--7 days of one another and have a very short lifespan of only 6--10 days. This suggests that this species is a true denizen of boreal climatic conditions, i.e. short, warm summers and long cold winters.


FLIGHT-TIME

Univoltine. Both sexes are strongly attracted to light between late May and early July, depending on locality, with the main flight period around the first 10 days of June (Skvortzov & Thomson, 1974). In the southern Urals, from mid June until early July (Nupponen & Fibiger, 2002).

However, if reared under warm conditions in captivity this species will produce a partial to full second brood, indicating that this may also happen under natural conditions (Roger Perkins, pers. comm. 2002).


EARLY STAGES

OVUM: Glossy, greenish yellow, rather large for size of moth (2.3 x 2.0 x 1.9mm) and dorso-ventrally flattened. Each female deposits fewer than 100 eggs, singly, on the underside or petiole of a leaf, hatching 10--12 days later.


Egg of Laothoe amurensis amurensis, Omsk, Siberia, Russia. Photo: © Tony Pittaway. Egg of Laothoe amurensis amurensis, Omsk, Siberia, Russia. Photo: © Frank Deschandol.

LARVA: Full-fed 65--80mm. Dimorphic: bluish-green with a blue horn, and yellowish-green with a horn of the same colour.


Newly emerged first instar larva of Laothoe amurensis amurensis, Omsk, Siberia, Russia. Photo: © Frank Deschandol. Part-grown first instar larva of Laothoe amurensis amurensis, Siberia, Russia. Photo: © Jean Haxaire. Second instar larva of Laothoe amurensis amurensis, Omsk, Siberia, Russia. Photo: © Frank Deschandol.

The newly-emerged larva is pale green with faint yellow markings appearing after feeding. In the second instar, it assumes its final coloration and form, which is bluish green (sometimes dark green) with white oblique lateral stripes on abdominal segments 1--8 and covered in white tubercles. Resembles that of Laothoe populi populi, except that the spiracles are larger and a pair of enlarged tubercles are present dorsally on thoracic segment 2; these tubercles become more noticeable as the larva grows (Pelzer, 1989). The spiracles are white, ringed with brown, and the short horn is yellowish-green or bluish, dotted laterally with white. As in Laothoe populi populi, it assumes a light plum colour prior to pupation.


Third instar larva of Laothoe amurensis amurensis, Omsk, Siberia, Russia. Photo: © Frank Deschandol. Third instar larva of Laothoe amurensis amurensis, Siberia, Russia. Photo: © Tony Pittaway. Fourth and final instar larva of Laothoe amurensis amurensis, Omsk, Siberia, Russia. Photo: © Frank Deschandol. Fourth and final instar larva of Laothoe amurensis amurensis, Omsk, Siberia, Russia. Photo: © Frank Deschandol. Fourth and final instar blue-green larva of Laothoe amurensis amurensis, Siberia, Russia. Photo: © Mark Boddington Final instar yellow-green larva of Laothoe amurensis amurensis, Siberia, Russia. Photo: © Tony Pittaway. Fourth and final instar yellow-green larvae of Laothoe amurensis amurensis, Finland. Photo: Kimmo Silvonen. Fourth and final instar blue-green larva of Laothoe amurensis amurensis, Siberia, Russia. Photo: © Jean Haxaire.

On hatching, the larva commences feeding immediately on mature leaves. At first, these are skeletonized but, with increasing size, whole leaves are consumed except for the midrib (Skvortsov & Thomson, 1974). However, like the larva of Laothoe populi populi, it is a wasteful feeder, with large segments of leaf being chewed off and falling to the ground. It feeds at night and, at first, rests by day stretched out under a leaf. In the second and later instars it assumes a sphinx-like attitude with its head hunched under the thorax; only the last 2--3 pairs of prolegs cling to the leaf. Fully-grown larvae tend to rest singly along a petiole, high up in mature trees where their colour enables them to blend superbly with the surrounding blue-green aspen leaves. When feeding on Populus, most individuals complete only four instars before pupation; some, however, pass through five instars, as do those feeding on Salix. This stage takes about 40--50 days, the resulting mature larva being larger than that of Laothoe populi populi.

Occurs from late June to early August. In Siberia, larvae can sometimes be so abundant as to constitute a pest (Gninenko, 1998).

Major Hostplants. Populus tremula and P. lancifolia (Elämet, 1954)

Minor Hostplants. Salix and other Populus spp.

PUPA: 30--43mm. In colour and shape, almost identical to that of Laothoe populi populi, except for the presence of a two-tier cremaster. Pupation normally takes place after only about four days in an unlined chamber, 2--3cm deep in the soil at the base of a tree or in a grass tussock. The overwintering stage.


Female pupa of Laothoe amurensis amurensis, Omsk, Siberia, Russia. Photo: © Frank Deschandol. Female pupa of Laothoe amurensis amurensis, Omsk, Siberia, Russia. Photo: © Frank Deschandol. Male pupa of Laothoe amurensis amurensis, Omsk, Siberia, Russia. Photo: © Frank Deschandol. Male pupa of Laothoe amurensis amurensis, Omsk, Siberia, Russia. Photo: © Frank Deschandol.

PARASITOIDS

Ichneumonidae: Netelia testacea (Gravenhorst), N. vinulae (Scopoli).


DISTRIBUTION

From southern Finland (Elämet, 1954; Nordstroem & Wahlgren, 1961), eastern Poland (Derzhavets, 1984), Belarus (Merzheevskaya et al., 1976), Estonia (Petersen, 1924; Thomson, 1967; Skvortsov & Thomson, 1974), Latvia and Lithuania (Kazlauskas, 1984), across european Russia (recorded as far north as Irael' (Tatarinov, Sedykh & Dolgin, 2003), northern Kazakhstan (Danner, Eitschberger & Surholt, 1998), western Siberia to the Altai Mountains of both Russia (Zolotarenko, Petrova & Shiryaev, 1978; Viidalepp, 1979) and China (Zhang, D. Y. et al., 1986). Although quite widely distributed in northern Europe, its occurrence may go undetected for long periods due to low population densities and a preference for remote, inaccessible regions. However, new localities are regularly being discovered as moth-traps are increasingly deployed in wilder regions.

Reported as being 'common' in Daghestan, southern Russia (Abdurahmanov, 1999), but this may be a mistake as this region of the Caucasus is well outside the normal range of this species.

Extra-limital range. Southern and eastern Siberia, Tuva ASSR, southern Yakutia (Kaimuk et al., 2005), Buryatia, Amurland, Ussuri, Sakhalin Island (Zolotarenko, Petrova & Shiryaev, 1978; Dubatolov, 1991), the Kurile Islands (Dubatolov, 1991), northern Mongolia, north-eastern China (Heilongjiang; northern Nei Mongol) and Japan (Hokkaido; Honshu). Records from areas of China southwest of Jilin Province are erroneous and refer to the closely related Laothoe sinica. Records from Korea (Kim, Nam & Lee, 1982) need confirmation as some may also be of Laothoe sinica; however, all specimens examined so far have been Laothoe amurensis amurensis.


OTHER SUBSPECIES

None (see Taxonomic note iii.)


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