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Genus EuceraphisBirch aphidsOn this page: Euceraphis betulae betulijaponicae gillettei papyrifericola punctipennisGenus Euceraphis [Calaphidini]Euceraphis are rather large active but fragile aphids with long thin legs. All adults, apart from oviparae, are winged insects. They secrete a bluish white wax, often in the form of tufts on their legs. The antennae are usually longer than the body. The birch-feeding species may have black dorsal abdominal markings. The cauda is knobbed and the anal plate is rounded. The oviparae are large, apterous, yellowish to dark brown with dark dorsal abdominal markings, and with the posterior abdominal segments extended into an ovipositor-like structure. Euceraphis is a genus of 6 or more species living on the young shoots or the underside of birch and alder (Betulaceae). Adults may be found as accidentals on many plants besides their true hosts. They have a sexual stage in their life cycle, but do not host alternate and are not attended by ants. One species is considered a pest of ornamental birch varieties. Euceraphis betulae (Silver birch aphid) Europe, North America, AustraliaAdult winged viviparae of Euceraphis betulae have the head and thorax black above and below, and a pale green to pale yellow abdomen. They are covered with bluish-white wax. The dorsal abdomen may be unmarked, or have transverse black bands (common in spring and autumn) or black patches on abdominal tergites IV and V. The fundatrix in spring always has multiple dark cross bands (cf. Euceraphis punctipennis the fundatrix of which never has dark bands or patches on abdominal tergites IV & V). The base of antennal segment VI is usually 0.8-1.32 times longer than the second hind tarsal segment (cf. Euceraphis punctipennis which has the base of antennal segment VI usually 1.33-1.75 times longer than the second hind tarsal segment). The legs and antennae are usually quite dark. Note that recently moulted specimens may be pale and lack wax. The body length of Euceraphis betulae alates is 3.0-4.2 mm.
Immature Euceraphis betulae are green with conspicuous short black-tipped siphunculi. The silver birch aphid lives on the undersides of leaves of silver birch (Betula pendula). Sexual forms occur from September to November. Euceraphis betulae occurs throughout Europe and has been introduced to North America and Australia. Euceraphis betulijaponicae (Oriental birch aphid) East AsiaAll adult viviparae of Euceraphis betulijaponicae are alate. Immatures (see first picture below) are greenish yellow with little wax. Mature alatae (see winged individuals in both pictures below) are pale green or greenish yellow, covered in bluish wax. The antennae are brownish yellow, with the apices of segments II & IV, as well as all of V & VI fuscous; the antennae are nearly twice body length. There are 20-40 oblong secondary rhinaria of different sizes along antennal segment III. The second hind tarsal segment (HTII) is 0.70-1.28 times antennal segment I (cf. Euceraphis betulae and Euceraphis punctipennis, which have HTII 1.24-1.75 times antennal segment I). The rostrum is dark at the apex with the apical rostral segment (RIV+V) 0.12-0.15 mm long, usually about 0.57-0.67 times longer than HTII (cf. Euceraphis papyrifericola in north-east USA & Canada, which has RIV+V 0.14-0.17 mm long, usually 0.67-0.79 times longer than HTII). The siphunculi are short, but longer than broad, and the cauda is knobbed. The body length of Euceraphis betulijaponicae alatae is 3.4-4.2 mm.
Both images above copyright zdk0812, under a creative common licence. Euceraphis betulijaponicae is found on various birch (Betula) and alder (Alnus) species, but sexual reproduction is apparently limited to Asian white birch (Betula platyphylla var. japonica) and its closest relatives Asian black birch (Betula dahurica), Betula platyphylla subsp. kamschatica, and Betula pendula subsp. mandshurica = Betula alba subsp. mandshurica. Oviparae and males have been found in October. These aphid species is found in Japan, China, and north into east Siberia. Euceraphis gillettei (American alder aphid) North AmericaAll adult viviparae of Euceraphis gillettei are alate. Immatures (see first picture below) are pale green mottled with dark green, and have pale siphunculi. Adult alatae (see second and third pictures below) have a pale yellow head and prothorax, pale brown meso- and metathorax (=hind thorax), and a pale yellowish-green abdomen mottled with darker green. The base of antennal segment VI is 2.64-3.67 times longer than the apical rostral segment (RIV+V) (cf. Euceraphis quednaui on Betula occidentalis, which has the base of antennal segment VI 1.72-2.75 times longer than RIV+V). The hairs on antennal segment III are much shorter than the basal diameter of that segment (cf. Clethrobius comes, which has the hairs on that segment much longer than basal diameter of that segment). There are never any dark markings on the dorsal abdomen, and there is sparse bluish-white wax on the legs and antennae. The legs are pale with the apices of the tibiae and the entire tarsi black. The siphunculi are pale, short and flared. The cauda is pale and knoblike. The body length of adult Euceraphis gillettei alatae is 2.5-3.5 mm.
Images above by permission, copyright Claude Pilon, all rights reserved. Euceraphis gillettei is an active species feeding on the leaves of alder (Alnus spp.). Oviparae and alate males occur in September-November. Euceraphis gillettei is found over much of Northern America, from British Columbia and Alasaka to Newfoundland, and from California to New Jersey. Euceraphis papyrifericola (Paper birch aphid) North AmericaAll adult viviparae of Euceraphis papyrifericola are alate. Immatures (see first picture below) are green with dusky siphunculi. Adult alatae (see second picture below) have a light brown thorax and a pale green abdomen, and are frequently covered with bluish-white wax which may form tranverse segmental bands on the dorsal abdomen. In spring and summer they usually have no dorsal abdominal pigmentation, but in autumn the sexuparae often have dark sclerites in the centre of tergites IV & V. Discrimination from other Euceraphis species depends on antennal characteristics. The base of antennal segment VI has only 1 hair (cf. Euceraphis lineata, Euceraphis mucida & Euceraphis quednaui, all of which usually have more than 1 (2-12) hairs on that segment). The second hind tarsal segment (HTII) is usually 0.7-1.28 times the length of antennal segment I, and usually shorter (0.7-1.1 times) than the terminal process (cf. Euceraphis betulae & Euceraphis punctipennis, both of which usually have HTII 1.24-1.75 times the length of antennal segment I, and usually longer (0.9-2.3 times) than the terminal process.) The siphunculi and cauda are both pale. Note: Euceraphis papyrifericola is very similar to, and closely related to, the Japanese species Euceraphis betulijaponica, and it could be regarded as a subspecies thereof.
Images above by permission, copyright Claude Pilon, all rights reserved. The main host of Euceraphis papyrifericola is paper birch (Betula papyrifera), but it may also be found on gray birch (Betula populifolia) and mountain paper birch (Betula cordifolia). The paper birch aphid feeds on the undersides of leaves (and small twigs?) and, like other Euceraphis, is very active. Sexuales - oviparae and males - occur in late August to October. Euceraphis papyrifericola is found in north-east USA and across Canada. Euceraphis punctipennis (Downy birch aphid) EuropeAdult winged forms of Euceraphis punctipennis have a pale green abdomen and are covered with bluish-white wax. Their head and thorax are dark brown. Dorsal black patches when present are usually confined to abdominal tergites IV and V. Dark cross bands are never present on fundatrices in spring (distinguishes specimens from Euceraphis betulae, at least in spring!). The base of antennal segment VI is usually 1.33-1.75 times longer than the second hind tarsal segment (cf. Euceraphis betulae which has the base of antennal segment VI usually 0.8-1.32 times longer than the second hind tarsal segment). The body length of Euceraphis punctipennis adult alates is 3.0-4.8 mm. Immature Euceraphis punctipennis are green with conspicuous short black-tipped siphunculi. The downy birch aphid lives on the undersides of leaves of downy birch (Betula pubescens). Sexual forms occur in October and November. Euceraphis punctipennis occurs throughout Europe.
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