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Genus EulachnusPine needle aphidsOn this page: Eulachnus agilis brevipilosus pumilae rileyi thunbergi tuberculostemmatusEulachnus are small, narrow and elongate greenish to olive brown aphids with long limbs. The siphunculi are slightly elevated, rim-like structures. Their antennae are 6-segmented. The Eulachnus genus comprises about 17 species, all of which live on the needles of Pinus. They are cryptic when feeding, but very active when disturbed. The best-known species of Eulachnus show preferences for certain Pinus species, but none of them are strictly confined to one host species. Eulachnus agilis (Spotted green pine needle aphid) Europe, Asia, North AmericaEulachnus agilis apterae are spindle-shaped and small. They are bright green with numerous dark spots and no wax (see first picture below). Their antennae are about 0.4-0.5 times as long as the body. The third antennal segment is more than 0.25 mm long and bears hairs 20-130 &mum; long (cf. Eulachnus brevipilosus which has the third antennal segment less than 0.24 mm. long and bearing hairs less than 20 μm long.). The long antennal hairs of Eulachnus agilis are clearly visible in the second image below. The legs are rather pale with the hind legs often having mottled pigmentation. Hairs on the hind tibia are longer than the tibia diameter. The body length of the adult Eulachnus agilis aptera is 1.6-2.3 mm.
The spotted green pine needle aphid may be found feeding on old needles of many pines (Pinus spp.), but it is especially common on Scots Pine (Pinus sylvestris). It does not host alternate. Oviparae and alate males are produced in October-November, and the oviparae lay eggs singly on leaf scars on the branches. Eulachnus agilis occurs throughout Europe and parts of Asia, and has been introduced to North America. Eulachnus brevipilosus (Light green pine needle aphid) Europe, Asia, North America, New ZealandApterae of Eulachnus brevipilosus are spindle-shaped and slender. They are light green with numerous faint spots and no wax (cf. Eulachnus agilis which is bright green with numerous very dark spots). The antennae have six segments, and are about 0.4-0.5 times body length (cf. Essigella californica which has very short 5-segmented antennae). The name 'brevipilosus' indicates the aphid is short-haired. The third antennal segment is less than 0.24 mm. long and bears hairs less than 20 µm long (cf. Eulachnus agilis which has the third antennal segment more than 0.25 mm long and bears hairs 20-130 µm long). Also, the setae on the third antennal segment are no longer than the greatest diameter of that segment. The capitate hairs on the dorsal side of the hind tibia are no longer than the diameter of tibia at its midpoint (see micograph below). The legs are rather pale. The body length of an adult aptera is 1.4-2.2 mm.
The light green pine needle aphid may be found feeding on needles on pines, especially on Scots pine (Pinus sylvestris) and stone pine (Pinus mugo). It does not host alternate. According to Blackman & Eastop (1994), sexual morphs have not been found - and they overwinter as viviparae. However, Zondag (1983) reports (perhaps wrongly) that sexual forms occur in Europe. Eulachnus brevipilosus occurs throughout Europe and parts of Asia, and has been introduced to North America and New Zealand. Eulachnus pumilae (Japanese pineneedle aphid) Central & East AsiaAdult apterae of Eulachnus pumilae (see first picture below) are spindle-shaped, with the body bright green to yellowish green. Antennae are dusky on the distal end of segments III-VI, and legs have the ends of the femora and all the tibiae dusky. Antennae are slender, 0.38-0.40 times body length; hairs on segment III are very small, only 0.27-0.40 times the basal diameter of the segment. The rostrum reaches nearly to the second coxae, with the apical rostral segment (RIV+V) bearing 2 accessory hairs (cf. Eulachnus cembrae in Europe, which is without accessory hairs on RIV+V). RIV+V is 0.39 times as long as the second hind tarsal segment (HTII) (cf. Eulachnus thunbergi, which has RIV+V 0.57-0.59 times HTII). The legs are very long, with many short stiff hairs. The hairs on abdominal tergites I-VI do not arise from scleroites (cf. most other Eulachnus species, including Eulachnus thunbergi, which have hairs on tergites I-V all or mostly arising from separate small rounded scleroites). The siphunculi are very small, with a narrow cone-shaped base, and are not hairy. The cauda is broadly semi-rounded with many long hairs, which are longer than those on the front, and not capitate. Body length of adult Eulachnus pumilae apterae is 2.4-2.5 mm.
Images above copyright Onidiras under a Creative Commons License. The alate viviparae of Eulachnus pumilae (see second picture above) resembles the aptera in body colour & shape, with a green or yellow-green elongate body. The antennae and legs are dark. The rostrum reaches nearly to the second coxae. The legs are very long and slender, with many short stiff hairs which are much shorter than those on the head. The hind tibiae are longer than the antennae. The wings are hyaline, with the pterostigma and veins pale yellow. Eulachnus pumilae is monoecious on the needles of pine (Pinus) species of subsection Cembrae, namely Japanese white pine (Pinus parviflora), Japanese stone pine (Pinus pumila), Korean pine (Pinus koraiensis) and rarely eastern white pine (Pinus strobus). It is holocyclic, with sexuales (oviparae & alate males) occurring in South Korea in early November. Eulachnus pumilae is found in northern India, east Siberia, Korea and Japan. Earlier reports of the species from Europe referred to the very similar Eulachnus cembrae (see Kanturski & Wieczorek, 2014 for comparison of sexual forms of the two species). Eulachnus rileyi (Active grey pine needle aphid) Europe, Asia, North & South America, AfricaWingless female viviparae of Eulachnus rileyi are very elongate spindle-shaped, and vary in colour from dark olive green to orange-brown or grey. They have prominent blackish setae on the dorsum. Older specimens become covered in bluish-grey wax (see first picture below), sometimes with tufts of wax filaments posteriorly. The hind pair of legs and other pairs to a variable extent are dark brown to black. The siphuncular cones are reduced to small blackish rings. The body length of Eulachnus rileyi apterae is 2.3-3.0 mm.
Winged viviparae are similar to apterae, but with the head and thorax darker, and less prominent setae on the abdomen. The active grey pine needle aphid can be found feeding on the needles of many species of pines (Pinus spp.). In Europe it occurs more commonly on European black pine (Pinus nigra) and mountain pine (Pinus mugo) than on Scots pine (Pinus sylvestris). Eulachnus rileyi are cryptic when feeding, but become very active when disturbed. The species is found in Europe, the Mediterranean area and south west Asia and has been introduced into Africa south of the equator and America. Eulachnus thunbergi (Hori pineneedle aphid) East & Southeast Asia, Australia & New ZealandAdult apterae of Eulachnus thunbergii (see two pictures below, and at NIBR) are elongate spindle-shaped, dirty green to yellowish brown with numerous hairs, on dark scleroites, covered with bluish white wax. In the pictures below the wax is thickest between segments, producing a striped appearance. Antennae were reported by Ghosh (1982) as 0.50-0.59 times body length (but see note below), with the terminal process 0.17-0.19 times the base of antennal segment VI; the longest hair on segment III is 1.5-1.6 times the basal diameter of that segment. The rostrum reaches the mid-coxae or a little beyond, with the apical rostral segment being 0.57-0.59 times the second hind tarsal segment. Fore femora are dark and thick, and less than 3.75 times longer than their maximal width. The abdominal dorsum has large black hair-bearing scleroites on abdominal tergites I-V in two irregular transverse rows on each tergite (see clarified mount at Carver & Kent (2000)); the anterior row has more scleroites than the posterior row (cf. Eulachnus agilis & Eulachnus rileyi, which never have more scleroites (often only 2) in the anterior than in the posterior row). Tergite VIII has a pair of brown sclerotic bands which may fuse into a single band. Siphunculi are small, and hardly elevated, and the cauda is brown to dark, with many long fine hairs. The body length of adult Eulachnus thunbergii apterae is 2.3-3.2 mm. Immatures are usually green, with less wax coating than the adults.
First two images above copyright Jake David Maclennan under a creative common licence. The alate vivipara of Eulachnus thunbergii (see below) has an elongate green body with dark transverse bars; body colour is obscured by the wax banding between the abdominal tergites and along the dorsal midline as well as on the head and thorax. The antennae bear 2-5 secondary rhinaria on segment III, with 1 on segment IV. The media vein on the forewing is once-branched and obsolete (=vestigial) on the basal part; the pterostigma is dark brown, and the radial sector, cubitus & anal veins are bordered with brown. Eulachnus thunbergii feeds on the needles of two native Asian pine species, Formosa pine (Pinus taiwanensis), and Japanese black pine (Pinus thunbergii). It is also found on (planted) loblolly pines (Pinus taeda). Inouye (1970) notes that it was fairly common in Japan, especially on and amongst the tender pine needles. This species is very active. Alate viviparous females mostly appear in the second generation. Alate males and oviparous females appear in October in the north of Japan. They have also been found in India (Raychaudhuri et al., 1983), but continuous parthenogenetic reproduction seems likely in warmer areas. The species is native to east and south-east Asia (India, Vietnam, China, Japan, Korea, Siberia, Taiwan, Java, Philippines), and has been introduced to Australia and New Zealand. Eulachnus tuberculostemmatus (Tuberculate pineneedle aphid) Southern Europe, North Africa, AsiaAdult apterae of Eulachnus tuberculostemmatus are narrowly spindle-shaped, pale green to greenish yellow with small brown dorsal spots. Antennae are brown, paler at the base. The legs are pale yellowish-green or greenish ochreous, with dusky tips to the tibiae and dusky tarsi. Antennae are about 0.5 times body length with a short, blunt terminal process. The longest hairs on antennal segment III are 20-50 µm long, with rarely more than one hair over 40 µm (cf. Eulachnus nigricola & Eulachnus brevipilosus, which have hairs on segment III less than 20 µm long; & cf. Eulachnus agilis, which has longest hairs on that segment 65-95 µm). The rostrum is long, reaching past the third coxae. The abdomen has with many small brown dorsal tubercles from which arise short stiff hairs. Abdominal tergites I-III have the longest hairs 15-40 µm long, pointed, and hardly pigmented. The tibiae have long dark spine-like hairs on one side, shorter ones on the other and over the surface. The siphunculi are round and inconspicuous, only slightly raised above the surface. The cauda is semicircular, with long pale hairs. Body length of adult Eulachnus tuberculostemmatus apterae is 1.4-2.7 mm. Immatures are yellowish green with dusky spots.
Image above copyright Francisco Rodriguez (Faluke), via inaturalist, under a Creative Commons License. Alate viviparae of Eulachnus tuberculostemmatus (not pictured here, but see biodiversidad) have the head and thorax brownish, the antennae, ends of tibiae and tarsi brown, and the abdomen pale grass-green, speckled with black spots and with faint transverse bands. The head has four large slightly capitate hairs in front and two rows of four on the vertex, arising from tubercles. The abdomen has rows of hairs coming from the darkened tubercles. The fore and mid pairs of legs are moderately long with normal coxae; the hind pair are very long, with large and thick coxae, and very long tibiae. Eulachnus tuberculostemmatus is monoecious on various warm temperate pine species (Pinus spp.). It is especially found on Aleppo pine (Pinus halepensis), but is not uncommon on several other species including Turkish pine (Pinus brutia), maritime pine (Pinus pinaster), stone pine (Pinus pinea) and black pine (Pinus nigra). Populations appear to be clonal, since no sexual morphs have been recorded. Reproduction appears to be entirely parthenogenetic. The tuberculate pineneedle aphid is found in southern Europe, the Mediterranean area including North Africa, and Asia eastward to Pakistan and China.
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NIBR.jpg "Eulachnus thunbergii (hori pineneedle aphid) alate vivipara on Pinus (pine) needle; NIBR.")
