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Cervaphis [Macrosiphini]Cervaphis are quite small aphids characterised by the presence, in the apterae, of long branched marginal hair-bearing processes. The head has a pair of two-branched processes, with a hair at the tip of each branch. Antennae are 4-5 segmented, with a terminal process 1.0-1.5 times the base of antennal segment VI. The eyes are triommatidia. The apical rostral segment is 1.7-2.5 times the second hind tarsal segment. The prothorax is fused with the head. The thoracic segments each have a pair of two-branched hair-bearing processes. Abdominal tergite I has a pair of one branched marginal processes, tergite II has a pair of one branched pleural process, and tergites III-VII have marginal processes, all hair bearing. The dorsum of tergites I-II has one branched processes. Tergite VIII has a plate with 5-10 hairs, the two middle hairs on a process. The siphunculi are long, cylindrical, slightly curved outwards and a little swollen subapically, where there is a ring of small hairs. The cauda has 6 hairs with a median process. In Cervaphis alatae the processes are reduced to low, flat hair-bearing tubercles, except on the head. Cervaphis has four or five species in India and south-east Asia. They feed on a variety of trees and shrubs, especially in the Tiliaceae (Grewia, Microcos, Schoutenia), Fagaceae (Quercus, Castanea), Malvaceae (Theobroma), and Fabaceae (Cajanus). They have also been recorded from plants in several other families. Sexuales have only been recorded for one of the species. Cervaphis rappardi is regarded as an important pest of pigeon pea in India. Cervaphis rappardi (Bristly cacoa aphid)Adult apterae of Cervaphis rappardi (see pictures below of Cervaphis rappardi indica) are yellowish or greenish, with pale appendages. The body is broadly oval, with marginal branched processes on all tergites, but with the branched processes very much reduced in size - especially on abdominal tergite II. The frontal processes, including their apical hair, are up to just over half as long as the antennae. Antennae are 0.21-0.34 times the body length, and normally 3 segmented. The rostrum has the apical rostral segment very slender and acute, and 1.89-2.40 times as long as the second hind tarsal segment. The tergum is strongly sclerotic, dorsally smooth, but below the marginal branched processes is conspicuously warty. Dorsal abdominal hairs are very blunt, often club-shaped with nearly globular apices, and extremely numerous (cf. Cervaphis schouteniae, which has dorsal abdominal hairs all more-or-less acute, lanceolate, or sometimes slightly bifurcate). Marginal processes on the abdomen have pointed or bifurcate hairs at ends of lateral branches, but dorsal branches bear very blunt or club-shaped hairs like those on mid-dorsal processes (cf. Cervaphis schouteniae, which has marginal processes either with bifurcate hairs at ends of lateral branches, or with an acute hair on one or two dorsal branches). The siphunculi are about as long as the antennae, evenly pale, with one or two scattered hairs, and 4-5 hairs in a ring near the apex where the siphunculus is suddenly narrowing to the small flange. The cauda is pale brown with 4 (?6) hairs and a median process. Body length of adult Cervaphis rappardi apterae is 1.2-1.7 mm.
Images above by permission, copyright Sunil Joshi & Poorani, J. Aphids of Karnataka (accessed 12/2/20). Alatae of Cervaphis rappardi (not pictured) are very different from the apterae. They have an olive-green abdomen, and darker head and thorax. Marginal branched processes are absent, or reduced to low tubercles bearing a great number of tiny hairs; the frontal processes are still recognisable as short, nearly acute horns, with numerous tiny hairs. Hairs on the dorsum are still very numerous, but very small. The antennae are 5-segmented, with 9-11 very large, bulging, somewhat tuberculate, secondary rhinaria. Antennal hairs are up to as long as the diameter of antennal segment III. The siphunculi are blackish, and thin. The wings have the veins in the fore wings quite black, but not bordered, and with the anterior half of the pterostigma colourless; the veins in the hind wing are paler. Immatures are a paler green than the adults, and have similar, but shorter, processes. The nominate subspecies, Cervaphis rappardi rappardi, is found in Southeast Asia on flowers, flowerstalks, and sometimes on leaves, young shoots, or young fruit of cocoa plants (Theobroma cacao, Malvaceae). They are often attended by ants (Dolichoderus spp.). Feeding may cause flower heads to shrivel and fall off. Colonies also occur on rambutan (Nephelium lappaceum, Sapindaceae), and possibly Erycibe grandiflora (Convolvulaceae) and Aglaia sp. (Meliaceae). The other subspecies, Cervaphis rappardi indica, is found on pigeon pea (Cajanus cajan) in India (Assam, Karnataka, West Bengal).
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