Observations on the biology of Afrotropical Hesperiidae (Lepidoptera) principally from Kenya. Part 4. Hesperiinae: Aeromachini and Baorini
Author
Cock, Matthew J. W.
Author
Congdon, Colin E.
text
Zootaxa
2012
3438
1
42
journal article
44508
10.5281/zenodo.246331
8bc74a10-7de0-4e39-8fc6-142a14d01b07
1175-5326
246331
Borbo fatuellus fatuellus
Hopffer, 1855
(
Figures 17–18
)
Subspecies
fatuellus
occurs throughout sub-Saharan Africa and in
Yemen
, and additional subspecies have been described from São Thomé and the
Comoros
(
Evans 1937a
,
Larsen 1984
). A form with grey scaling on the UNH (
cinerea
Holland
) has been associated with the dry season in eastern and southern Africa (
Evans 1937a
) and both forms are common in
Kenya
.
Van Someren (1939)
reports
B. fatuellus
as fairly numerous in the grass and bush along the forest margins from
4,500–6,000 ft
. (
1370–1830 m
) in the Chyulu Hills, and it is not uncommon in the Makardara Forest (
Sevastopulo 1974
). I consider it an occasional but widespread species of open forest throughout
Kenya
. TCEC has found it mainly in woodland in
Tanzania
, but extending into open areas in forest.
Adult behaviour
Adults settle low on grasses and shrubs when they are easily caught (
Dickson & Kroon 1978
). These perches are used to maintain territories as described by
Henning
et al
. (1997)
, who note that adults also feed at flowers and damp patches.
Food plants
The recorded food plants are grasses.
Le Pelley (1959)
lists
Cenchrus purpureus
(=
Pennisetum purpureum
) in
Uganda
,
Forsyth (1966)
gives
Paspalum
sp. and
Zea mays
(maize) in
Ghana
, and
Sevastopulo (1975)
lists
Panicum trichocladum
,
C. purpureus
(=
Pennisetum purpureum
) and grasses generally from East Africa (this entry appears against both
B. fatuellus
and
B. lugens
, and I assume it applies to both). Sevastopulo (unpublished) does not mention
Panicum trichocladum
as a food plant, so the origin of this record is not clear.
Vuattoux (1999)
reared ten specimens in
Côte d’Ivoire
from several different grasses: five on
Setaria barbata
, two on
Digitaria atrofusca
(=
D. seminuda
), one on
Setaria megaphylla
and two on unidentified grasses.
Larsen (1991)
lists
Ehrharta
,
Oryza
,
Zea
,
Cenchrus
(=
Pennisetum
) and
Panicum
, but I have been unable to confirm
Oryza
from the literature.
Ackery
et al
. (1995)
list only
Ehrharta
,
Cenchrus
(=
Pennisetum
),
Panicum
and
Setaria
.
Later,
Larsen (2005)
lists
Setaria
,
Cenchrus
(=
Pennisetum
),
Panicum
,
Setaria
and
Digitaria
; he also reports his observation of oviposition on
Imperata cylindrica
in
Nigeria
.
In
South Africa
,
Murray (1959)
,
Pringle
et al.
(1994)
and
Henning
et al
. (1997)
give
Ehrharta erecta
and
Setaria megaphylla
(=
sulcata
) as food plants, while
Dickson & Kroon (1978)
also include “other grasses not specifically recorded”.
I have reared
B. fatuellus
on
Megathyrsus maximus
(=
Panicum maximum
) and another (non-flowering) grass in
Kenya
, and?
Panicum
(
s.l
.) sp. in
Côte d’Ivoire
. TCEC raised a specimen from an ovum laid on an unidentified grass in a forest glade at Ambangulu in the West Usambaras,
Jun 2001
.
Leaf shelters
Two
4–5mm
n-2 caterpillars collected on an unidentified grass in
Côte d’Ivoire
(89/205B) made a two-cut shelter just before the leaf tip, by cutting two notches from the edge of the leaf,
25mm
apart, and rolling the flap downwards to make a tube. The larger caterpillars shelter in a rolled leaf, and feeding is distal to this (
Henning
et al
. 1997
).
Caterpillar
Clark (in
Dickson & Kroon 1978
) illustrates two different caterpillars of this species from
South Africa
. The first resembles one of those illustrated here (Figure 17.2); the second has the dark line in each half of the face narrower, and not extending basally, and the clypeus more extensively white.
Henning
et al
. (1997)
include a photograph of a caterpillar from
South Africa
, similar to that shown here as Figure 17.3–4. Although Clark (in
Dickson & Kroon 1978
) documents five instars, Sevastopulo (unpublished) recorded six at the
Kenya
coast.
Up until the end of the penultimate instar, caterpillars have a plain, dark head; that of instar n-2 measured 1.2 x
1.2 mm
(91/41). The head of the penultimate instar measures 1.8 x
1.9mm
wide x high (n=2); it may be uniformly dark, but in one case (91/41) had diffuse slightly paler areas on the epicranium, in front of the stemmata and on the frons; body green with a white dorsolateral line and a diffuse pale lateral line (87/23). Only in the final instar do the caterpillars develop a variably marked black and white head (
Figure 17
), 2.5 x
2.9mm
wide x high (n=3). A description was prepared of a final instar caterpillar collected at Arabuko-Sokoke Forest on
M. maximus
(87/23), which measured
18mm
when newly moulted and
37mm
when mature. Head wider near base; slightly indent at vertex; dark brown; face white, with dark brown sutures, and a black line running from about half way between top of adfrontals and vertex, parallel to epicranium, meeting adfrontal suture a little below apex; basal part of this line then curves laterally and becomes more diffuse; a vertical line in basal half of clypeus (similar to Figure 17.4, but the brown line is narrower in the described specimen); scattered short, pale, erect setae. T1 concolorous with body. Body light yellowish green; dorsal line darker green, becoming translucent as the caterpillar matures; well marked pale dorsolateral and lateral lines, becoming more diffuse, as the caterpillar matures; ventrally, spiracles and all legs whitish. I recorded that the wax glands develop ventrally in the mature final instar caterpillar as a double patch on A8 and a single patch on A9 for one caterpillar (87/23, Arabuko-Sokoke Forest), on A5 and A6 for another (91/41, Kakamega Forest), and on A7–A8 for a third (89/205B,
Côte d’Ivoire
); further observations are needed to clarify this. The final instar takes about 13 days. Development from eclosion to pupation can take 33 days at the coast (Sevastopulo unpublished).
FIGURE 17
. Final instar caterpillars of
Borbo fatuellus
.
1
, dorsolateral view; collected as penultimate instar caterpillar on
Megathyrsus maximus
, Arabuko-Sokoke Forest
, 28.ix.1987; moulted to final instar 2.x.; photographed 12.x., 37 mm; pupated 15.x., ref. 87/23;
2
, detail of head, anterolateral view; collected as n-2 caterpillar on unidentified grass, Kakamega Forest, 17.vi.1991; moulted to final instar 7.vii.; photographed 7.vii., pupated 18.vii.; 91/41;
3
, final instar, anterodorsolateral view, collected as small caterpillar on unidentified grass (?
Panicum
(
s.l
.) sp.), Adiopodoumé, Côte d’Ivoire, 28.v.2005; moulted to final instar 17.vi.; photographed 17.vi., 22mm; pupated 30.vi.; ref. 89/205B.
4
, final instar, anterolateral view of head; details as 3.
Pupa
The pupa, typical of the group, is formed partially exposed in a leaf only partly rolled and held with silk basal and distal to the pupa (
Figure 18
). The shelter is lined with white waxy powder, but this is not on the pupa itself. Male pupa 87/23 was
31mm
long and about
5mm
at the widest; slender, with a straight frontal spike
2.5mm
long; light green; narrow subdorsal lines about
1mm
apart. Pupation takes 10–19 days.