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Dark-veined birch aphidsOn this page: Calaphis betulaecolens betulicola flava leonardi magnoliae
Genus Calaphis [Calaphidini]
Calaphis are delicate pale-coloured aphids with rather long thin legs. Their antennal tubercles are well-developed and the antennae are longer than the body. They sometimes have distinctive markings and/or dark wing veins, and the radial sector in the forewing is absent or indistinct. In some Calaphis species all viviparae are alate, but others have both apterous and alate viviparae. The genus is sometimes mis-spelt as Callaphis.
There are about 15 Calaphis species, 11 of which are in North America, two are European, and one is east Asian. All except one live on birch (Betula spp.). They have a sexual stage in their life cycle, but do not host alternate and are usually not attended by ants.
Calaphis betulaecolens (Common American birch aphid)
All adult viviparae of Calaphis betulaecolens are alate. Their immatures (see first picture below) are apterous, yellowish and have long near-capitate pleural hairs. The alatae (see second picture below) are bright lemon yellow without dorsal markings. The antennae of the alate have segment III dark, segments IV & V with the basal portions light and the apical portions dark, and segment VI with just the apex of the base dark. Antennal segment III has twelve to eighteen oval secondary rhinaria. The apical rostral segment (R IV+V) is usually more than 0.14 mm long, as long as or a little longer than second hind tarsal segment (HT II) (cf. Calaphis leonardi, Calaphis viridipallida and Calaphis flava, whose R IV+V is usually less than 0.14 mm long and shorter than HT II). The forewing veins are heavily bordered with fuscous and the tibiae are dark. The siphunculi are entirely pale (cf. Calaphis betulicola, which has the siphunculi with the apical halves dark brown to black.) The body length of Calaphis betulaecolens alatae is 3.0-3.5 mm.
Both images above by permission, copyright Claude Pilon, all rights reserved.
Calaphis betulaecolens is mostly found on the leaves of yellow birch (Betula alleghaniensis =Betula lutea) and paper birch (Betula papyrifera); also occasionally on silver birch (Betula pendula) and gray birch (Betula populifolia). The species has been reported to be common in the northern part of Illinois, where the paper birch is native, and likely to be found wherever there are trees of that species. At times Calaphis betulaecolens are abundant and the eggs formed regular masses on the low branches and watersprouts of its host. Sexuales (apterous oviparae and alate males) occur in autumn. Calaphis betulaecolens is widely distributed in North America.
Calaphis betulicola (Black-tipped dark-veined birch aphid)
Apterae of Calaphis betulicola (see first picture below) are pale green or yellowish, with dark apices to antennal segments, femoro-tibial joints, tibial apices and tarsi. The head and thorax are pale. The antennae are longer than the body, and the terminal process is clearly longer than the base of the last antennal segment. On Calaphis betulicola the secondary rhinaria are placed towards the middle of the segment (cf. Calaphis flava which has the secondary rhinaria near the base of antennal segment III). The siphunculi are pale but with dark brown tips (cf. Calaphis flava which has the siphunculi pale or a little dusky at the flange). The body length of Calaphis betulicola is 2.0 to 2.3 mm.
Winged individuals (see second picture above) have characteristically darkened wing veins, and siphunculi with the apical halves dark brown to black.
Calaphis betulicola is found on the undersides of leaves of range of Betula species, including Betula pendula and Betula pubescens, usually on seedlings and small trees less than 1 meter high. It has also been recorded as living on Betula nana in Scotland and Sweden. It is distributed from northern Europe across Russia to China and Japan, as well as in North America (USA and Canada).
Calaphis flava (Yellow dark-veined birch aphid)
The apterae of Calaphis flava (see first picture below) are pale green or yellowish with dark tips to the antennal segments, femoral-tibial joints, tibial apices and tarsi. The antennae are longer than the body and curving. Most secondary rhinaria on antennal segment III are placed towards the base of the segment (cf. Calaphis betulicolawhich has them placed towards the middle of the segment). The siphunculi of Calaphis flava are entirely pale or rarely have slightly dusky tips (cf. Calaphis betulicola which has the apical halves of its siphunculi dark). The body length of adult apterae is 1.9-2.7 mm.
The Calaphis flava alate (see second picture above and first below) has the wing veins somewhat darkened (cf. Calaphis betulicola, which has wing veins strongly darkened).
Calaphis flava favours small bushes of downy birch (Betula pubescens), but is also found on young growth of larger trees and of other birch species. Alate males and apterous oviparae can be found in autumn on various Betula species. It is widespread in Europe eastward in Asia to Siberia and has been introduced to South Africa, Australia and North America.
Calaphis leonardi (Grey birch aphid)
All adult viviparae of Calaphis leonardi are alate. Their immatures (see first picture below) are apterous, and pale whitish green. The alate adults(see second picture below) are pale yellowish-green and orange with brown-black antennae, tibiae and tarsi, and dark wing veins. The apical rostral segment (R IV+V) is usually less than 0.14 mm long, and is shorter than the second hind tarsal segment (HT II) (cf. Calaphis betulaecolens, which has R IV+V usually more than 0.14 mm long, and as long as or slightly longer than HT II). The forewing veins are dark, but not heavily bordered with fuscous (cf. Calaphis viridipallida and Calaphis flava, which have the forewing veins heavily bordered with fuscous). The tibiae are dark (cf. Calaphis viridipallida and Calaphis flava, whose tibiae are pale except at the base and apex). The body length of adult Calaphis leonardi apterae is 3.0-3.33 mm. The species was first described by Quedneau in 1971.
Both images above by permission, copyright Claude Pilon, all rights reserved.
Calaphis leonardi only feeds on the leaves of gray birch (Betula populifolia). Sexuales occur in September-October - the oviparae are wingless with dark dorsal markings, but males have yet to be described. The gray-birch aphid is an American species found in north-eastern USA and eastern Canada.
Calaphis magnoliae (Dark-veined magnolia aphid)
All adult viviparae of Calaphis magnoliae are alate. The adult vivipara (see picture below) has the head and abdomen pale straw-yellow, with an orange yellow thorax. The hairs on the head and thorax are quite long, but are shorter on the abdomen. The antennal tubercles are low. Their antennae are very long and mostly pale, but with black areas near the middle and apex of antennal segment III (cf. Calaphis magnolicolens, which has segment III only gradually darkening distally). In addition, the bases and apices of segments IV and V, and all of segment VI except the base are dark. The terminal process is about 5.3 times as long as the base of segment VI. The secondary rhinaria on antennal segment III are circular or oval, arranged in a row with 3 or 4 in the pale basal region, and 5-9 in the dark area; there are also a few rhinaria on antennal segments V and VI.
Image above by permission, copyright Akihide Koguchi, all rights reserved.
The forewing veins of Calaphis magnoliae are heavily bordered with fuscous, especially distally (cf. Calaphis magnolicolens, which does not have the forewing veins bordered with fuscous). The stigma is very pale with a black tip, and there is no radial sector vein. The hind wings are pale throughout. The abdomen has five pairs of spinal tubercles which are concolorous with the body (see picture above). The femora are mainly pale, but the bases and distal halves of the tibiae and the tarsi are dusky or dark. The siphunculi are small pale truncate cones. The cauda is knobbed, and the anal plate is bilobed. The body length of alate Calaphis magnoliae viviparae is 1.4-2.2 mm.
Calaphis magnoliae feeds on the leaves of kobushi magnolia (Magnolia kobus) and black lily magnolia (Magnolia liliflora). The life cycle is assumed to be monoecious holocyclic, but sexual morphs are so far undescribed. The dark-veined magnolia aphid is found in East Asia (Japan and Korea).