McMullen, Conley K.

English

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OBSERVA TIONS' ON INSECT VISITORS TO FLOWERING PLANTS
OF ISLA SANTA CRUZ.
PART 11. BUITERFLIES, MOTHS, ANTS, HOVER FLIES' AND STILT BUGS
by
Conley K. McMullen
Department 01Botany. University 01 Maryland, College Park, Maryland 20742
In Part I of this paper the author mentioned the depauperate condition of the Galapagos insect fauna
which is emphasized by the presence of only one species of bee, Xylocopa darwini, the endemic carpenter
bee (McMullen, 1985): This relative dearth ofinsects is also apparent in the groups discussed here. Within
the archipelago only ten species of butterfly, 144 species of'moth, seven species ofhover fly, twenty-two
species of ant, and one species of stilt bug have been reported (Linsley and Usinger, 1966; Rindge, 1973;
Hayes, 1975; Linsley, 19,77;Froeschner, 1985).
Even fewer reports have been made as to what flowering plants are visited by these insects. Williams
(191 I) mentioned observing the Galapagos sulfur butterfly, Phoebis sennae (recorded as Callidryas
eubele) (Pieridae), at flowers of Cordia lutea (Boraginaceae), Opuntia (Cactaceae), and Gossypium
(Malvaceae) on Isla Isabela. He also reported that the hawk moth Enyo lugubris delanoi (recorded as
Epistor lugubris delanol) (Sphingidae) visited Cordia lutea at Villamil, Isabela in the bright sunlight, and
Manduca rustica calapagensis (recorded as Protoparce rustica calapagensis) (Sphingidae) visited flowers of
Cordia lutea and Clerodendrum molle (Verbenaceae) at Tagus Cove, IsabeIa at dusk. Beebe (1923)
reported that Phoebis sennae made visits to Cordia and Gossypium on Isla San Cristóbal. He also
mentioned that the moth Atteva hysginiella (Yponomeutidae) visited Cassia (Fabaceae), Cordia, and
Gossypium. Wheeler (1924) reported that the an t Monomoriumj7oricola (Formicidae) visited the nectaries
of Cordia lutea and Opuntia helleri on Isla Genovesa.
Hayes (1975) mentioned that the carmine hawk moth, Agrius cingl/latus (Sphingidae) visited flowers of
Cacabus miersii (Solanaceae), lpomoea (Convolvulaceae), and Opuntia during the day. Also mentioned
were Utetheisa galapagensis (Arctiidae) which was observed flying around plants of Scalesia affinis
(Asteraceae) at dusk, Heliothis cystiphora (Noctuidae) which visited flowers of Encelia hispida
(Asteraceae) during the day on Isla Santa Fe, Paectes arcigera (Noctuidae) seen near Cryptocarpus
pyriformis (Nyctaginaceae), and Pseudoplusia includens (Noétuidae) which visited flowers of
Clerodendrum molle and Cordia.
The only mention of insect visitors to flowering plants specifically on Isla Santa Cruz, other than Xylocopa
darwini, is that of Rick (1966). He reported observing flies (Diptera) visiting flowers of Borreria
(Rubiaceae).
The observations reported here took place on the southern slope of Santa Cruz during the months of
October 1983 through March 1984. Observations of insect visitors to flowering plants were conducted in
each of the seven major vegetation zone. Tables 1-41ist the flowers and visitors observed during this time,
along with locations, level of activity and whether the plants are endemic or non-endemic.
AII of the 22plants listed represent new insect visitation reports to flowers on Santa Cruz. Only three ofthe
22 have been reported before for the archipelago as a whole. Among the insect visitors Leptotes
parrhasioides, Disc/isioprocta stellata, Wasmannia auropunctata, Tapinoma melanocephalum, Paratrechina
longicornis, Paratrechina vaga, Toxomerus crockeri, Metacanthus galapagensis, and the unidentified
pyralid moth are newly reported as insect visitors to flowers of the archipelago.
Pollen was actually observed only on the butterfly Leptotes parrhasioides. Because of this it would be
inappropriate to labeI all of these insects pollinators. However, the author does echo Linsley (1966) in
suggesting that butterflies, moths, flies and ants might have possible roles in pollination beca use they play
this part in continental areas. Toxomerus crockeri was very active in several flowers, as were many of the
butterflies and moths. Many ant species were also very active in several flowers. This is not highly unusual
because of the ant's heavy use of sugar and palien for food, and although ant morphology is not well
adapted for pollen transport, the possibility does exist that with such a high level oftraffic throughout an
inflorescence a pollination event might occur. The same possibility applies to the stilt bug, Metacanthus
galapagensis, during its feeding visits to flowers.
21
Noticias de Galapagos v.43 1986
The majority of insects was observed during daylight hours. However, the moths were much more active
towards dusk with the pyralid and Agrius cingulatus active at night.
There appears to be no strong correlation between flower color and insect visitor other than the expected
visits made by hawk moths to larger white flowers such as those of Carica papaya (Caricaceae) and
Clerodendrum molle var. molle. In general, the insects visited the few different colored flowers that were
available. The one obvious trend, that also shared by Xylocopa darwini, was toward non-endemic plants.
Justicia galapagana (Acanthaceae), Cordia leucophlyctis (Boraginaceae), Jaegeria gracilis (Astraceae), and
Gossypium barbadense var. darwinii were the only endemics observed to be visited by insects other than the
carpenter bee. Therefore, these results would seem to further substantiate Linsley et al. (1966) in their
observation that insect visitors may have pro ved more usefui in the establishment of the non-endemic
(weedy plants and adventives) flora than for the older endemic species.
ACKNOWLEDGEMENTS
The author would like to thank the following individuals for their help in identification of insect
specimens: F.H. Rindge of the American Museum of Natural History, R.e. Froeshner and F.e.
Thompson of the National Museum of Natural History, e. Mitter and M.A. Solis of the University of
Maryland Entomology Department, and especially Rolf Meier. Special appreciation is extended to Rev.
and Mrs. e.A. McMullen for their support of this study.
LITERA TURE CITED
Beebe, W. (1923)Notes on Galapagos Lepidoptera. Zoologica 5: 51-59.
Froeshner, R.e. (1985) Synopsis of the Heteroptera or true bugs of the Galapagos Islands. Smithsonian
Contributions to Zoology 407: 1-84.
Hayes, A.H. (1975) The larger moths of the Galapagos Islands (Geometroidea, Sphingoidea, and
Noctuoidea). Proc. Calif. Acad. Sci., ser. 4, 40: 145-208.
Linsley, E.G. (1966) Pollinating insects of the Galapagos Islands. In: R.I. Bowman (ed.), the Galapagos
pp. 225-232. Univ. Calif. Press, Berkeley and Los Angeles.
Linsley, E.G. (1977) Insects of the Galapagos (Supplement). Occas. Papers Calif. Acad. Sci. 125: 1-50.
Linsley, E.G. and R.L. Usinger (1966) Insects ofthe Galapagos Islands. Proc. Calif. Acad. Sci., ser. 4, 33:
113-196.
Linsley, E.G., Rick, e.M., and S.G. Stephens (1966) Observations on the floral relationships of the
Galapagos carpenter bee. The Pan-Pacific Entomologist 42: 1-18.
McMullen, e.K. (1985) Observations on insect visitors to flowering plants of Isla Santa Cruz. Part 1.The
endemic carpenter bee. Noticias de Galapagos, No. 42.
Rick, C.M. (1966) Some plant-animal relations on the Galapagos Islands. In: R.I. Bowman (ed.), The
Galapagos, pp. 215-224. Univ. Calif. Press, Berkeley and Los Angeles.
Rindge, F.H. (1973) The Geometridae (Lepidoptera) of the Galapagos Islands. American Museum
Novitates 2510: 1-3\.
Wheeler, W.M. (1924) The Formicidae of the Harrison Williams Galapagos Expedition. Zoologica 5: 101-
122.
Williams, F.X. (1911) Expedition ofthe California Academy ofSciences to the Galapagos Islands, 1905-
1906. IlI. The butterflies and hawk-moths of the Galapagos Islands. Proc. Calif. Acad. Sci., ser. 4, 1:
289-322.
Table 1. Surnrnary of flower record s for butterflies on Isla Santa Cruz frorn October 1983-March 1984.
Planl Visited Insect VL~ltor Localion Activity
JUJlicia galapagana (E) [..eploles pa"hasioides Transition Zone, 3.5 km n. moderate
(Acanthaceae) (Lycaenidae) Puerto Ayora
Tournefortia psi/oslachya (N) [..eploles pa"hasioides Transition Zone, 3.5 km n. modera te
(Boraginaceae) (Lycaenidae) Puerto Ayora
Mormordica charanlia (CE) [..eploles pa"hasioides Transition Zone, 3.5 km n. low
(Cucurhitaceae) (Lycaenidae) Puerto Ayora
Vigna IUleola (N) !..eploles pa"hasioides Pampa Zone, 3 km n.
(Fahaceae) (Lycaenidae) Media Luna
Cuphea racemosa (1) Leploles pa"hasioides Pampa Zone, 3 km n.
(Lythraceae) (Lycaenidae) Media Luna
Gossypium barbadense (E) Phoebis Sennae Arid Zone,
var. dar",inií (Pieridae) Darwin Station
(Malvaceae)
low
high
low
22
Noticias de Galapagos v.43 1986
Sida rhombifalia (1) Leptates pan ~asiaides Transition Zone, 3.5 km n. high
(Malvaceae) (Lycaenidae) Puerto Ayora
COl/1l11icmpl/Jtl/berosl/s (N) Leptotes parrhasioides Arid Zone, low
(Nyctaginaceae) (Lycaenidae) Darwin Station
I'lumbaga scandens (N) l'haebis sennae Transition Zone, 3.5 km n. low
(Plumbaginaceae) (Pieridae) Puerto Ayora
Leptates parrhasiaides Transition Zone, 3.5 km n. low
(Lycaenidae) Puerto Ayora
Tribulus cistaides (1) Leptotes parrhasiaides Arid Zone. low
(Zygophyllaceae) (Lycaenidae) Darwin Station
Table 2. Summary of flower records for moths on Isla Santa Cruz fram October
Plant Visited Insect Visitor Localion
CO/'dia leucophlyctis (E) DiscliJiaprocta stellata Arid Zone,
(Boraginaceae) (Geometridae) Darwin Station
Taurn~rartia psilastachya (N) Unidentified genus Arid Zone,
(Boraginaceae) (Pyralidae) Darwin Station
Carica papaya (CE) Agrius cingulatus Arid Zone.
(Caricaceae) (Sphingida'e) Darwin Station
Clemdcndrum malle (N) Unidentified genus Arid Zone.
var. malle (Sphingidae) Darwin Station
(Verbenaceae)
Table 3. Summary of flower records for ants on Isla Santa Cruz fram October 1983-March
Plants Visited Insect Visitor Location Activity
Justicia galapagana (E) Wamrannia aurapunctata Transition Zone, 3.5 km n. low
(Acanthaceae) (Formicidae) Puerto Ayora
A,'icennia gCl11linans (N) Paratrechilla langicarnis Littoral Zane.
(Avicenniaceae) (Formicidae) Tortuga Bay
Tapillama mclanacephalum Littoral Zane.
(Formicidae) Tortuga Hay
Wamrannia aurapunctata Arid Zone.
(Formicidae) Darwin Station
Paratrechilla vaga Arid Zone.
(Formicidae) Darwin Station
Wasmanllia aurapunctata Transition Zone. 3.5 km n.
(Formicidae) Puerto Ayora
Tapinoma melanacephalum Littoral Zone.
(Formicidae) Tortuga Hay
Wamranllia auropunctata Arid Zone.
(Formicidae) Darwin Station
Wasmannia auropunctata Transition Zane. 3.5km n.
(Formicidae) Puerto Ayora
Unidentified genus Arid Zone.
(Formicidae) Darwin Station
1
CO/'dia lutea (N)
(Horaginaceae)
Mormordica charantia (CE)
(Cucurbitaceae)
l'msnpis julifTora (N)
(Fabaceae)
Setaria geniculata (N)
(Poaceae)
Capsicum frutescens (CE)
(Solanaceae)
Clerodcndrum molle (N)
var. molle
(Verbenaceae)
1983-March 1984.
Activity
high
low
high
moderate
1984.
I)igh
high
moderate
low
moderate
low
high
high
low
Plant Visited
Ageratum canazoides (1)
(Asteraceae)
Jaegeria gracilis (E)
(Asteraceae)
Olphea racemasa (1)
(Lythraceae)
Polygonum opelousanum
(Polygonaceae)
Diodiá radula (1)
(Rubiaceae)
Cordia lutea (N)
(Boraginaceae)
Table 4. Summary of flower record s for hover flies and stilt bugs on Isla Santa Cruz
from October 1983-March 1984
Insect Visitar Locafion Activity
Toxomerus crockeri Pampa Zane, 3 km n. high
(Syrphidae) Media Luna
Toxomerus crockeri Pampa Zone, 3 km n.
(Syrphidae) Media Luna
Toxomerus crockeri Pampa Zane. 3 km n.
(Syrphidae) Media Luna
Toxomerus crockeri Pampa Zane. 3 km n.
(Syrphidae) Media Luna
Toxamerus crockeri Pampa Zane, 3 km n.
(Syrphidae) Media Luna
Metacanthus galapagensis Arid Zane.
(Berytidae) Darwin Station
(E) endemic (N) native (1) introduced weed (CE) cultivated escape
23
high
high
low
low
high
Noticias de Galapagos v.43 1986


Observations on insect visitors to flowering plants on Isla Santa Cruz, Part II. Butterflies, moths, ants, hover flies and stilt bugs

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Observations on insect visitors to flowering plants on Isla Santa Cruz, Part II. Butterflies, moths, ants, hover flies and stilt bugs

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