Caprona pillaana Wallengren 1857

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 : 31-36

Caprona pillaana Wallengren 1857 ( Figures 23–28 )

Originally described from Natal (Kaffraria), C. pillaana is found north to Ethiopia and from there West to Nigeria, as a savannah species. Evans (1937) recognised two forms: pillaana the wet season form, and cassualalla Bethune Baker the dry season form which he separated as paler, with the outer third of the hind wing brownish ochreous. Caprona cassualalla is now recognised as a distinct species restricted to Angola and South–West Africa ( Vári 1974; Dickson & Kroon 1978; Ackery et al. 1995; Larsen 2005).

Kielland (1990) suggests this is a woodland species. In Kenya it seems to be associated with dryland forests, both dense (e.g. Kibwezi) and open (e.g. Ndara Ranch), and although widespread in such habitats ( Larsen 1991), it is particularly found from the coast inland to Meru. van Someren (1939) notes it from the lower plains below 1,220m (4,000m), around the Chyulu Hills, and Sevastopulo (1974) from Marere Forest, Shimba Hills, where it is not uncommon.

Adult behaviour

I have not observed the adults in the field, and the only adult that I have caught had flown into a restaurant which acted as a malaise trap (Diani Beach, 11 Apr 1990). However, the caterpillars are quite easy to find on fresh growth of suitable Grewia spp. and I believe the females ( Figure 23 ) must range widely to locate oviposition sites.

Observations reported in Dickson & Kroon (1978) suggest this species comes quite readily to flowers including Fabaceae , while Kielland (1990) reports that adults are attracted to water. However, Pinhey (1965) suggests that visiting flowers or mud is only an occasional activity. Larsen (1991) comments on the territorial behaviour shown by males and has found that adults came to roadside Tridax flowers in Arabia (T.B. Larsen, pers. comm. 2010).

Food plants

I have found caterpillars quite commonly on Grewia bicolor (Malvaceae) ( Figure 24 ) in the drylands from the Rift Valley to Voi (Magadi Road 94/300, 94/301; Kibwezi Forest 88/47, 91/32; Kibwezi Junction 91/15; Irima– Ndi 89/ 28; Taita Hills 89/17; Mt Sagalla 840m 91/1; Ndara Ranch 91/48). At the coast caterpillars can be found on Grewia plagiophylla (Arabuko–Sokoke Forest 87/24, 88/83, 88/118; Nyali 88/84) and Grewia sp. (Diani Beach, 87/24), and I have seen shelters probably of this species on G. ectasicarpa (Arabuko–Sokoke Forest, 88/83). I have several times tried to rear caterpillars through in Nairobi on related food plants such as G. similis and Hibiscus calyphyllus , but although they may feed for a while, they have invariably died.

Dollman (unpublished) reared this species from caterpillars found on “muresha” (unidentified) at Solwezi, Zambia, in all months except August and September; he also noted it on “chitumpu”, i.e. Syzygium guineense (Myrtaceae) (N.D. Riley in Dollman unpublished). He recorded Netrobalane canopus from the same food plants. Subsequent records have not replicated this species or family food plant record (nor for N. canopus ), so it should be discounted until confirmed. On a 1989 visit to the Ukiriguru Agricultural Research Institute, near Mwanza, Tanzania, I noted a specimen of C. pillaana in the insect collection reared at Ukiriguru, 10 Mar 1958 on Sterculia sp. (Malvaceae) by I.A.D. Robertson (ref. 9454). Sevastopulo (1974, 1975) lists Grewia spp. as food plants, and he reared this species from a caterpillar collected on Grewia sp. at Nyali (Sevastopulo unpublished). van Someren (1974) lists Grewia similis as a food plant in East Africa, although my observations failed to confirm this. In South Africa Dombeya rotundifolia is a food plant ( Murray 1959; Dickson & Kroon 1978; Pringle et al. 1994). Kielland (1990) Larsen (1991, 2005) and Heath et al. (2002) repeat these records. Pringle et al. (1994) add a record of G. flava (by Woodhall) in southern Africa. New records from southern Africa increase the list from this area to D. burgessiae , G. flava , G. monticola and S. quinqueloba (Malvaceae) ( Henning et al. 1997).

Ovum

Ova are laid singly on the leaf upper surface in mid lamina. They measure about 1.0mm in diameter at the base; weakly ribbed; covered with long linear scales, about 2.5mm long, and 0.1mm at the widest, tapered at ends; when fresh these scales are dark grey-brown, but over time become bleached white. The ova and their covering resemble those of Netrobalane canopus .

Leaf shelters

The first shelters are usually one-cut oval shelters cut from the leaf lamina (6–8 x 5 mm), but occasionally a triangular two-cut shelter from the edge of the lamina (7 x 5 mm) is made. The leaves with stage 1 shelters did not necessarily have hatched eggs on them, suggesting the caterpillar may change leaves after hatching. The second shelters are similar, but larger: 9 x 6.5 mm one-cut shelters in the lamina and 15 x 9 mm two-cut shelters from the leaf edge. One stage 2 shelter was observed to have a double row of very small holes, top and bottom (but not reared to confirm identification). The stage 3 shelter is formed between two leaves, placed one on top of the other. Only once have I collected a pupa in the field (Magadi Road, 29 May 1994, 94/301), and its shelter on Grewia bicolor was more elaborate. The two terminal leaves were used, one above the other. The lower leaf was almost entire, apart from a long cut from the apex, adjacent to the midrib; the distal part of the leaf separated from the midrib by this cut was bent upwards along a line at right angles to the cut. One half of the upper leaf was largely consumed except for the area under which the pupa was formed, but still supported by major veins; robust silk strands were used to hold it convex relative to the lower leaf and well above the lower leaf leaving an open chamber with the pupa on the dorsal surface, not dissimilar to those formed by Eagris sabadius . I have attempted to clarify this rather complicated arrangement in a diagrammatic way in Figure 25 .

Caterpillar

There are five instars. The last two instars last 9 and 18 days respectively. The different instars are all similar ( Figures 26–27 ). The head capsules, width x height, are as follows: instar 1 0.9 x 0.8mm (n=7), instar 2 1.1 x 1.1mm (n=9), instar 3 1.9 x 1.8mm (n=7), instar 4 2.3 x 2.1mm (n=9), instar 5 3.5 x 3.2mm (n=3). Thus the head becomes slightly wider than high as the caterpillar matures. The following notes were prepared from caterpillars collected at Kibwezi Forest on Grewia bicolor , 12 Jun 1988 (died in the fifth instar and preserved in ethanol), and supplemented by microscopic examination of caterpillar remains from all collections.

Fifth instar 13mm, growing to 20mm ( Figure 26 ); head dark, covered with hairs: those of the apices dark; a diffuse broad brown band across face, and otherwise pale brown; those of the dorsal 1/3 of head erect, c. 0.75mm long, branched and sub-branched; those of face short, branched, recumbent; those around mouthparts longer, branched, directed downwards. T1 with broad orange-brown dorsal shiny plate on posterior margin, extending to half way down side of segment; divided by a pale dorsal line. Body yellow green, elongated at A8–A9; surface warty, each supporting a short, pale stalked stellate hair. Spiracle T1 concolorous; other spiracles pale, inconspicuous. All legs concolorous.

The mature caterpillar painted in dorsal view by Dollman (unpublished) is more rounded, perhaps because it is ready to pupate. It also shows a faint dorsal line, and there are dark areas on the vertices of the head, which seem similar to those seen in Netrobalane canopus . Although Dollman noted the fine hairs of the body, he was unable to show these in his painting.

Earlier instars. Instar 4 ( Figure 27 ) similar to instar 5, but head with hairs dark on apices, pale brown in broad band across face and white otherwise; the longest hairs on the head are 0.3mm long; T1 dorsal plate dark brown, with pale dorsal line. The fourth instar caterpillar illustrated by Henning et al. (1997) is similar. Instar 3 similar to instar 4, but head with dark hairs on apices, a faint pale brown band across face, otherwise white, the longest hairs 0.2mm long. Instars 2 and 1 similar, but head with less dense hairs, dark on the apices, white elsewhere. In instar 2 in particular the posterior part of the body (A8–A9) may have a yellow or orange tint. Examining the early instars with the naked eye, the dark hairs on the apices of the head appear to be patches without hairs.

Pupa

Pupation is in the third leaf shelter, usually between two leaves, one above the other, and lasts 14–16 days in Nairobi, but nine days at the coast (Sevastopulo unpublished). The pupa is formed on the dorsal leaf, ventral side upwards against the leaf, supported with a Y-shaped girdle.

A third instar caterpillar collected at Kibwezi Junction on Grewia bicolor 8 Mar 1991 moulted twice and pupated 11 Apr in a shelter between a leaf and the rearing container, supported by a Y-shaped girdle; an adult male emerged after 14 days. Pupa 17mm ( Figure 28 ); frontal projection short (0.6–0.7mm), parallel sided, slightly bifurcate at the apex, black; spiracle T1 yellow, projecting; other spiracles pale brown. Pupa ground colour white, with no waxy powder; thorax and appendages tinged green and abdomen tinged yellow; black markings as follows: a thin cross dorsally on thorax, short end towards the head with anterior tip thickened, arms turned posteriorly just before 1/2 length; strong short dorsal line at posterior margin of thorax; triangular spot just anterior to top of cross on thorax; pair of subdorsal spots between this and frontal projection; lateral to these a large spot on the top of the eye; large spots on anterior and posterior margins of the eye; base of spiracle T1 surrounded by large black spot with smaller irregular spots immediately anterior and posterior; irregular black streak below eye, joining below frontal projection; a few fine dots at base of antenna; thin streak on base of T2 leg; a fine black line outlines the fore wing termen, dorsum, upper and lower margin of cell, veins 1–6; small streak on anterior margin of A1 adjacent to wing; dorsolateral row of eight spots on abdomen; abdominal spiracles surrounded by black; cremaster black laterally and ventrally; A6 and A8 narrowly black dorsally on posterior margin .

Figures

FIGURE 23. Adult female Caprona pillaana collected as pupa on Grewia bicolor, Magadi Road, 29 May 1994, adult 11 Jun, 94/301.

FIGURE 24. Grewia bicolor in flower on the Magadi Road, below Olepolos, 23 Mar 1991.

FIGURE 25. Diagram of pupal leaf shelter of Caprona pillaana using two leaves of Grewia similis, collected 29 May 1994, Magadi Road at first river crossing, (94/301). 1, the lower leaf, with a white line to show where the distal portion was bent upwards; 2, the upper leaf; 3, the two leaves in position. Moderate shading represents leaf upper surface of lower leaf; light shading represents leaf upper surface of upper leaf; unshaded areas are feeding damage; dark shading indicates the position of the pupa attached to the under surface of the upper leaf. Approximately 1.4 x life size.

FIGURE 26. Final (fifth) instar caterpillar of Caprona pillaana. 1, detail of head, frontal view, collected as fourth instar on Grewia bicolor 23 Jan 1991, Mt Sagalla, 840m, moulted to final instar 5–8 Jan, photographed 10 Jan, 91/1; 2, detail of head, lateral view, same data as (1); 3, dorsal view, collected on G.bicolor, 12 Jun 1988, Kibwezi Forest, photographed 27 Jun, 20mm, 88/43.

FIGURE 27. Fourth instar caterpillar of Caprona pillaana collected on Grewia bicolor, Mt Sagalla, 23 Jan 1991, photographed 27 Jan, 16mm, moulted to fifth instar 5–8 Feb, not reared, 91/1. 1, detail of head; 2, lateral view.

FIGURE 28. Pupa of Caprona pillaana collected as instar 3 caterpillar on Grewia bicolor, Kibwezi Junction, 8 Mar 1991, pupated 11 Apr, photographed 12 Apr, 17mm, 91/15. 1, dorsal view; 2, lateral view.