Eagris sabadius astoria Holland 1896

Cock, Matthew J. W. & Congdon, T. Colin E., 2011, Observations on the biology of Afro-tropical Hesperiidae (Lepidoptera) principally from Kenya. Part 2. Pyrginae: Tagiadini 2893, Zootaxa 2893 (1), pp. 1-66 : 9-18

Eagris sabadius astoria Holland 1896 ( Figures 1–9 )

Eagris sabadius astoria is found in wooded and disturbed situations (e.g. gardens), and in Kenya is commonest in the Central Highlands, especially around Nairobi, and extending to 2000m or more on Mount Kenya. It is widespread in western Kenya, but not as common. It is common around Nairobi, but although the caterpillars can almost always be found (see Table 3 of collections), the adults are not that regularly seen. van Someren (1939) reports it from the Chyulu Hills: a few specimens at mid altitudes of 1,525m (5,000 ft.) and plentiful in the mixed forest of the lava ridges, and in the Shimba Hills, Sevastopulo (1974) found it uncommon around Makadara Forest, but these records may refer to ssp. ochreana ( Larsen 1991) . In Tanzania ssp. astoria occurs from northern Tanzania east and south to the Njombe highlands. TCEC reared ssp. astoria from Mufindi, Iringa Region (approximately 8°30'S, 35°40'E) in Jul 2007.

Adult behaviour

The males when seen are usually perched or flying quite high up (3–4m). They fly rapidly and erratically, but usually can be recognised by the yellow colour of the underside ( Figure 1.2 ) which fades in the field in old specimens. In Ngong Forest they can be spotted flying around trees adjacent to the open tracks, whereas in Kakamega Forest they seem to prefer to perch lower down on bushes beside tracks. At rest, adults hold their wings flat or inclined slightly downwards. Only occasionally do they come to feed at flowers.

Food plants

This species is polyphagous within the families Sapindaceae and Malvaceae (including the former families Bombacaceae , Sterculiaceae and Tiliaceae ) ( Figure 2 ), and I have collected early stages from at least 14 different food plants (one more, det. as? Prunus sp. (001), was not adequately identified, but note there is an unpublished record from this genus at the end of this paragraph). I once found a pupa in Ololua Forest in a typical shelter on Achyranthes aspera (Amaranthaceae) ; however, this is not a food plant and doubtless the caterpillar strayed from the adjacent Hibiscus calyphyllus on which leaf shelters were present. Caterpillars seemed able to transfer between food plants quite readily, and most of those which I collected were reared through on Pavonia urens (Malvaceae) which I grew in my garden. The food plants, collection localities and months of collection are summarised in Table 3. In Tanzania, TCEC found caterpillars on Dombeya burgessiae (Malvaceae) and Allophylus spp. (Sapindaceae) , usually on the latter. Published records of food plants are summarised in Table 4. Two unpublished food plants that would benefit from confirmation are Prunus africana (Rosaceae) and Celtis sp. (Cannabaceae) (I. Bampton, pers. comm.).

1? = Collection not reared to adult. Ovum

Ova are pale with a translucent shell and turn dark before eclosion. They are 3/4-spherical, 0.9 mm diameter at the base (n=8, range 0.81–0.96mm) with 13 ribs (n=5, range 11–14) which join near the top to form a narrow ring ( Figure 3 ). The ova are laid on the leaf upper surface, close to the mid rib, often in pairs. As she lays the eggs, the female covers them with long, thin, pale scales from her abdomen tip ( Figure 3.1 ). The scales turn darker with age, so that parasitized eggs, for example, appear brown ( Figure 3.2 ). Eclosion is by eating a hole through the top of the egg, leaving most of the shell and its covering intact.

Leaf shelters

The first shelter is a one-cut shelter, usually oval (6–7 x 4–5 mm), cut from the middle of the leaf lamina ( Figures 4.1, 4.2 , 5 ), but occasionally cut from the edge. The second shelter may be similar (10–12 x 7–8 mm) ( Figures 4.3 , 5 ), but commonly a two-cut shelter, cut from the edge of the leaf lamina. The final shelter ( Figures 4.4 , 5 ) is normally cut from the leaf edge, but in the form shown in Figure 4.4 with a long stem, and elongate shelter, truncate distally due to the edge of the leaf from which it was cut. Sometimes, however, this final caterpillar shelter is formed with one leaf on top of another (e.g. on Allophylus rubifolius ). In making these shelters, the caterpillar leaves uncut the main vein of the portion of the leaf which will form the lid of the shelter, which thus remains green.

Caterpillar

Caterpillars in the first shelter feed nearby by perforating the leaf to eat out small compact holes ( Figure 4.1 ). This feeding is sufficiently distinct to enable separation of the shelter from that of Netrobalane canopus which makes a similar shelter on several of the same Malvaceae food plants, but skeletonises the leaf as it feeds. There are five or, at least in captivity, six instars. Early stages can be found more or less throughout the year ( Table 3), but my collections suggest that they are much commoner from July to November and January around Nairobi; there is no obvious reason for the absence of collections in May and December. Average instar durations (and the range and number of observations) which I have noted include: L2 9 days (1); L3/Ln–2 9 days (7–13, 3); Ln–1 14 days (8–21, 7); Ln 20 (12–29, 8).

Instars 1 and 2 are dark, rich red with a dull black-brown head ( Figure 6.1 ). The head of instar 1 measures 0.60 x 0.57mm wide x high (n=3, range 0.56–0.63 x 0.52–0.59mm), while that of instar 2 is 0.86 x 0.85 (n= 9, range 0.81–0.93 x 0.81–0.89).

Instar 3 is intermediate to the later instars, with a yellow dorsolateral line, and increasingly dark green, but often strongly tinted with red ( Figure 6.2 ).

Penultimate instar (mixture of instars 4 and 5). Light green ( Figure 7 ), due to a sprinkling of white dots on a green ground colour. The head varies from brown to dark brown. The head measures 2.38 x 2.29mm wide x high (n=31, range 2.04–2.81 x 1.89–2.78mm).

Final instar. The body ( Figure 8 ) is similar to that of the penultimate instar. The head measures 3.25 x 3.13 mm wide x high (n=36, range 2.93–3.70 x 2.74–3.52mm). Although the ranges of size overlap, the head of female caterpillars in the final instar is on average slight larger than that of the male: 3.37 x 3.21mm (n=15) compared to 3.13 x 3.03mm (n=14), t 27 =3.87, P<0.001 (based on head capsule width). The colouring of the head is variable from uniform light brown ( Figure 8.2 ), through intermediate forms with increasingly brown ground colour, and increasing amounts of dark brown at the vertex, in a stripe down the middle of the face, dorsally, around the stemmata, and in the darkest form the posterolateral region, leaving just a patch each side of the face that is paler brown ( Figure 8.1 ). Although the body appears smooth to the naked eye, under 40x examination with a binocular microscope it can be seen to be covered with very short, simple, pale setae, with scattered longer, simple, pale setae. Fully mature caterpillars are often strikingly pale, almost white, and this seems to be associated with the uniform pale brown head ( Figure 8.2 ). This variation is not linked to sex, food plant ( Malvaceae vs. Sapindaceae ) or the female colouring. The variation shown by this common species has made it difficult to distinguish early stages of other members of the genus without rearing them

Pupa

The pupa is formed in the final caterpillar shelter, which is characteristically suspended above the leaf from which the flap is cut ( Figure 4.4 ). As noted above, these shelters are not always formed on the host plant, and I once reared E. sabadius from a pupa in a shelter on Achyranthes aspera in Ololua Forest (see also E. lucetia and E. decastigma , for both of which pupae have been found on plants that are not food plants). The pupa is attached by the cremaster and supported by a Y-shaped silk girdle. There is no loose white waxy powder, but white markings on the pupa are due to a layer of white wax which can be easily scraped off. The pupal stage lasts about 14 days (19 observations, range 9–23).

A caterpillar collected 25 Jun 1987 on? Prunus sp. in Nairobi (87/1) pupated 12 Jul, and the following description was prepared 14 Jul; it turned dark on 26 Jul and a male emerged the following day. 15mm long, including frontal projection; intricately marked in white and brown, some of which has a bronze tone. Frontal spike 0.7mm long, 0.6 wide at apex which is weakly bifurcated. Eyes marked in white and two shades of brown. Dorsally on collar, two dark triangles with apex pointed forwards and rounded; thorax dorsally with obscure brown markings. Abdomen light brown dorsally; weak white dorsal line; narrow transverse dark line across dorsum on A3–A4; a broader, conspicuous bar each side of dorsal line A5; white dorsolateral area A3 and A4; below these a dark interrupted lateral line from A4–A9; below this a white transverse streak on anterior margin A5 and posterior margin of A4–A7; ventrally abdomen whitish yellow. Cremaster dark brown, plain, 3/ 4mm long. Wings with dorsum dark brown, remainder white with variable spots along veins. Other appendages pale whitish brown; apex of proboscis brown. T1 spiracle protuberant; orange-brown.

The frontal projection is variable which seems to be loosely linked to the size of the resultant adults. The length is 0.7mm on averages and varies 0.6–1.0mm, and the width at the apex averages 0.6 and varies 0.4–0.7mm. Pupae that produce small adults have the apex slightly bifurcate into dorsal and ventral halves, whereas pupae that produce normal adults are usually quadrifurcate; intermediate pupae show the dorsal protuberance divided laterally, but not the ventral one. On average, the proboscis sheath projects 2.4mm beyond the wing cases, varying 0.2– 3.2mm.

Natural enemies: I have reared egg parasitoids from this species on three occasions: Ngong Forest on Dombeya burgessiae (Malvaceae) 3.ii.1991; Ngong Forest on Grewia similis (Malvaceae) 1.x.1989, 16.ix.1990.

I have only once found a caterpillar attacked by a parasitoid. A second instar caterpillar collected from D. burgessiae in Ngong Forest on 3.ii.1991 was being fed upon by a solitary ectoparasitic eulophid larva which pupated naked in the host shelter a few days later, and emerged about six days after that.

The pupae are also attacked rarely, and only once did I rear a tachinid: from a pupa collected on Pavonia urens in Kakamega Forest (16.vi.1991, 91/33). The tachinid larva emerged from the pupa and was successfully reared. The host pupa was certainly that of an Eagris sp. but might have been that of E. lucetia , rather than E. sabadius . Unfortunately, I cannot now locate the tachinid or host pupa remains, although it is possible that they are in the NHM.

Having collected quite large numbers of caterpillars around Nairobi ( Table 3), and only once obtained one that was parasitized, I am confident, albeit somewhat surprised, that this species is not normally parasitized in the caterpillar stage. I am more surprised that the pupa does not seem to be commonly parasitized since in its shelter it seems dangerously exposed to small generalist pupal parasitoids such as Brachymeria spp. (Chalcididae) and eulophids, and yet of nine field collected pupae only one was parasitized. Perhaps further collecting will show it not to be as protected as it seems.

The comparison with Celaenorrhinus galenus opalinus (Butler) is interesting, as caterpillars of both are common around Nairobi. Celaenorrhinus galenus opalinus caterpillars are heavily parasitized while those of E. sabadius are barely affected, yet the adults of E. sabadius are equally common, or if anything slightly rarer than those of C. galenus .

Figures

FIGURE 2. Selected Kenyan food plants of Eagris sabadius astoria. 1, Hibiscus sp., Muguga, 11 Nov 1988; 2, H. calyphyllus, Ngong Forest, Nairobi, 12 Nov 1988; 3, Pavonia urens v. tomentosa, cultivated, Nairobi, Jun 1990; 4, Pavonia burchellii, Nairobi, 5 Nov 1989; 5, Cardiospermum grandiflorum, cultivated, Nairobi, 21 Jan 1990.

FIGURE 3. Egg of Eagris sabadius astoria, collected on Allophylus abyssinicus, New Blue Posts Inn, Thika, 17 Mar 1991 (91/ 18B). 1, fresh colouring, 18 Mar 1991; 2, dead / parasitized colouring, 28 Mar 1991.

FIGURE 4. Leaf shelters of Eagris sabadius astoria. 1, stage 1 shelter and associated feeding on Pavonia urens, Ololua Forest, Karen, Nairobi, 6 Mar 1988, 88/18; 2, lid of opened stage 1 shelter with instar 1 caterpillar, Ngong Forest, Nairobi, 1 Oct 1989, 89/ 70E; 3, stage 2 shelter on Cardiospermum grandiflorum (Sapindaceae), Nairobi, 12 Nov 1989; 4, stage 3 shelter on Grewia similis which contained a prepupa, Ngong Forest, Nairobi, 19 Nov 1989, 89/93.

FIGURE 5. Diagram of leaf shelters of Eagris sabadius astoria on Dombeya burgessiae, collected Aug 1987, Karen, Nairobi (87/8). Moderate shading represents leaf upper surface; light shading represents leaf under surface (of leaf shelters); unshaded areas are feeding damage. 1, half leaf with stage 1 and 2 shelters, and eclosed ovum indicated on the leaf under surface used in the stage 2 shelter; 2, whole leaf with stage 3 shelter, which contained a?fourth instar caterpillar. Scale approximately life size.

FIGURE 6. Early instar caterpillars of Eagris sabadius astoria. 1, second instar collected 1 Oct 1989, on Grewia similis, Ngong Forest, Nairobi, photographed 2 Oct 1989, 6mm, not reared, although another collected on same occasion was, 89/70D; 2, third instar caterpillar, collected 17 Oct 1988 on Abutilon longicuspe, Muguga, photographed 23 Oct 1988 when newly moulted, subsequently reared to adult, 88/94.

FIGURE 7. Penultimate instar caterpillar of Eagris sabadius astoria collected 10 Oct 1989 on Allophylus rubifolius, Karura Forest, Nairobi, photographed 11 Oct 1989, 15mm, moulted 13 Oct, adult female 1 Dec, 89/78A. 1, dorsolateral view; 2, detail of head.

FIGURE 8. Fifth instar caterpillars of Eagris sabadius astoria. 1, collected and photographed 19 Jul 1988 on Pavonia burchellii, Muguga, prepupa 29 Jul, female 15 Aug, 88/58; 2, collected and photographed 8 Oct 1989 on Allophylus ferrugineus, Karura Forest, Nairobi, 24mm, pupa 17 Oct; female 29 Oct, 89/77.

FIGURE 1. 1–3, Adults of Eagris sabadius astoria collected as caterpillars on Dombeya burgessiae, Ngong Forest, Nairobi, 8.x.1989, 89/74. 1, male emerged and photographed 1.xi.1989; 2, as (1) showing the underside; 3, female emerged and photographed 21.x.1989. 4, reared females: above, Kiambu, Tigoni Woods, caterpillar collected 19.vii.1987 on Pavonia urens, ref. 87/4(3); below, South Nyanza, NW side of Gwasi Hills, 1450m, caterpillar collected 7.ii.1991 on Grewia sp. (118), ref. 91/6A, scale bar = 1cm.

FIGURE 9. Pupae of Eagris sabadius astoria. 1, dorsolateral view, collected and photographed 19 Nov 1989 on Dombeya burgessiae, Ngong Forest, Nairobi, male 26 Nov; 89/92; 2, lateral view, collected as pupa 14 Jan 90 on Ceiba speciosa, Kyuna Estate, Nairobi, photographed 16 Jan, 17mm, male 20 Jan, 90/5B; 3, ventral view, collected 19 Nov 1989 as prepupa on Grewia similis, Ngong Forest, Nairobi, photographed 26 Nov, male 4 Dec, 89/93.