Caenides dacela Hewitson, 1876

Cock, Matthew J. W., Congdon, Colin E. & Collins, Steve C., 2014, Observations on the biology of Afrotropical Hesperiidae (Lepidoptera). Part 6. Hesperiinae incertae sedis: palm feeders, Zootaxa 3831 (1), pp. 1-61 : 52-54

Caenides dacela Hewitson, 1876

Caenides dacela was originally described from the island of Bioko (= Fernando Po) ( Hewitson 1876), and there are numerous records from Guinea and Sierra Leone (a Gambia record is in error) to Uganda, ( Evans 1937, Larsen 2005), southern Sudan (T.B. Larsen, pers. comm. 2013), western Kenya ( Larsen 1991), western Tanzania ( Kielland 1990) and northern Zambia ( Heath et al. 2002). The record from Kenya was based on material reared by MJWC, who on three occasions found caterpillars on one particular Phoenix reclinata palm in the northern part of Kakamega Forest. ABRI collectors have since reared this species from the same food plant near Kakamega ( Collins 2008) and it is likely to occur more widely, perhaps in other western areas of Kenya where the food plant occurs.

Adult behaviour. Not observed, but likely to be a dusk flier. Kielland (1990) says it visits flowering herbs and low bushes in shady forest.

Food plants. Le Pelley (1959), Sevastopulo (1975) and Kielland (1990) give P. dactylifera as the food plant, the first reference referring to Uganda. Heath et al. (2002) refer to a specimen reared by TCEC and I. Bampton, and give the food plants as P. dactylifera and Raphia spp. (repeated in Vande weghe 2010), but since TCEC did not rear C. dacela from these palms in his collaboration with Bampton, we discount these food plant records.

In Kakamega Forest, Kenya, MJWC collected this species from P. reclinata (not P. dactylifera as stated in Larsen 1991). TCEC reared it from the same food plant in western Tanzania (forests of Mpanda, Kigoma and Kagera), but from a rattan palm, Eremospatha sp. in northern Zambia.

Leaf shelters. The first instar shelter ( Kenya) is made either by cutting two notches from the edge of a leaflet and folding the resultant flap over upwards, or by cutting a notch from one side just before the apex of a leaflet, and pulling together the distal portion. The shelter of the young caterpillar ( Zambia) is in the tip of a tatty old leaflet, and the caterpillar is coloured to match ( Figure 54.1 ). The shelter has been opened, and the caterpillar is in the process of pulling it shut again. From a human perspective, this is not the sort of place one would look to find a caterpillar, so may be a good survival strategy for the caterpillar. The fifth instar caterpillar forms a shelter between two leaflets.

Ovum. Two ova collected on Phoenix in association with early stages of C. dacela (Alupe, near Busta, western Kenya, 18 Jun 2006, SCC) are thought to be C. dacela as they are not Zophopetes dysmephila , the species commonly found on Phoenix spp. These eggs are 1.5mm diameter, dome-shaped, with 31 weak ribs.

Caterpillar. The following notes are based on collection 90/76 on P. reclinata , north Kakamega Forest. There are five instars, the head capsules measuring 0.8 x 0.8, 1.2 x 1.2, 1.7 x 1.7, 2.4 x 2.7 and 3.7 x 4.0mm wide x high, respectively. The first instar has a uniformly dark head. The second instar caterpillars have a light brown head with the posterior margin dark; body green. The third instar is shown when newly moulted in Figure 53.1 : 8mm; head light brown, reticulate pattern faintly apparent on front of epicranial, posterior margin dark; body dark brown dorsally, light brown ventrally. The fourth instar, also newly moulted, is shown in Figure 53.2 : head similar to previous instar, but reticulate pattern slightly more evident; faint trace of lateral band. The mature fifth instar is shown in Figure 53.3–4 : 32mm; head with broad brown stripe down centre; light brown band down anterolateral margin; light brown posteriorly; dark posterior margin. Body dull grey; dorsal line dark; subdorsal and dorsolateral lines dull yellow; paler ventrolaterally and ventrally; anal plate paler on posterior margin; all legs concolorous; spiracles light brown, inconspicuous. The wax glands develop as a continuous ventral mass from A1 to A8. Two caterpillars collected in the first instar moulted after 6 days, and the following instars lasted 6, 8, 10 and 17–21 days respectively.

The caterpillars which TCEC documented from Tanzania and Zambia ( Figure 54 ) are compatible with those found in Kenya by MJWC ( Figure 53 ).

Pupa. The pupa is formed in a shelter of one or two leaflets, and held with a single strand silk girdle ( Figure 55 ); rather uniformly brown, no setae evident. The inside of the shelter and the cast final instar skin are well covered with white waxy powder, but the pupa only lightly so. The pupal stage lasts 20–24 days under Nairobi conditions.

Natural enemies. One of two ova collected by SCC at Alupe , western Kenya, 18 Jun 2006, had an egg parasitoid (probably Trichogrammatidae ) exit hole of 0.35mm diameter .

Figures

FIGURE 53. Caterpillars of Caenides dacela collected 20 Jul 1990 as n-3 instar caterpillar on Phoenix reclinata, north Kakamega Forest. 1, instar 3 caterpillar, dorsolateral view; moulted to 3rd instar 27 Jul; photographed 1 Aug; moulted to 4th instar 9 Aug; 8mm; 90/76C; 2, instar 4 caterpillar, dorsal view; moulted to 4th instar 9 Aug; photographed 10 Aug; moulted to 5th instar 14–20 Aug; 15mm; 90/76C; 3, full grown instar 5 caterpillar, dorsal view; moulted to 5th instar 14–10 Aug; photographed 31 Aug; pupated 5 Sep; 32mm; 90/76C; 4, instar 5 caterpillar, detail of head, dorsolateral view; moulted to 5th instar 14–10 Aug; photographed 21 Aug; pupated 5 Sep; 22mm; 90/76B.

FIGURE 54. Caterpillars of Caenides dacela from Tanzania and Zambia, TCEC. 1, young caterpillar in shelter on Eremospatha sp., Lisombo, north-west Zambia, 15 May 2000; 2, penultimate instar, on Phoenix reclinata, Minziro, Tanzania, 3 May 1994; 3, penultimate instar, as #1; 4, final instar on Eremospatha sp., Chikonke Stream, north-west Zambia, 17 May 2000.

FIGURE 55. Pupae of Caenides dacela. 1–2, dorsolateral view, collected on Eremospatha sp., Chikonke Stream, north-west Zambia, 26 May 2000; 3, lateral view, collected 20 Jul 1990 as small caterpillar on Phoenix reclinata, north Kakamega Forest, Kenya; pupated 5 Sep; photographed 7 Sep; adult 29 Sep; 90/76B.