1987] 
Windsor — Tortoise beetle, Acromis sparsa 
129 
abundant insect in second growth on the mainland at Frijoles, 4-5 
km away and is found in disturbed habitats across the Isthmus of 
Panama including areas of quite different mean annual rainfall (1.8 
m on the Pacific side versus 3.2 m on the Caribbean side). This 
beetle has become common along the El Llano-Carti Road (approx- 
imately 45 km east of Panama City), an area converted from forest 
to second-growth within the past 15 years. 
Quantitative observations of A. sparsa were made in mid-isthmus 
at three sites within 15 km of one another, primarily between 
August and November of 1978. The “mixed” site is a roadside tran- 
sect through grass and young forest along the Pipeline Road, 3-6 
kms NW of Gamboa (79° 42' W, 9° 07' N). The “field” site is an 
expanse of tall grass, occasional shrubs and vines at the beginning of 
the Pipeline Road, 2 km NW of Gamboa. The “forest” site is 
shaded 1 km transect along the Old Gamboa Road, 7 km SE of 
Gamboa. 
Food-plant 
The life history of A. sparsa is closely tied to a single host-plant, 
Merremia umbellata L. (Convolvulaceae). The range of M. umbel- 
lata includes S. Florida, W. Indies, Mexico, Central and South 
America and much of the Old World Tropics (Austin 1975). I have 
never observed A. sparsa feeding on other plant species although I 
have occasionally found larvae and pupae “stranded” on vegetation 
touching their food plant. Merremia umbellata is a common road- 
side vine which grows rapidly in the early wet season using support 
from grasses, dead shrubs, etc. to reach sunlight. Older plants have a 
substantial underground tuber which sends out a network of above- 
ground runners, each of which gives rise to numerous vertically 
climbing shoots. During the first four to six weeks of the wet season 
M. umbellata grows rapidly and may form a closed canopy over 
second-growth vegetation. Growth slows during the late wet and dry 
season and fewer leaves are supported. Flowering occurs in January 
of most years. 
Merremia umbellata has many casual and host specific herbivores 
including at least six species of Cassidinae. This is the richest 
assemblage of Cassidinae on a single plant species that I have 
observed in Panama. Of these species, only A. sparsa is subsocial, 
three are solitary in all stages and two have eggs in clutches — one of 
