1. A parasitoid web is a subset of a food web containing data on paras
itoids and their hosts; connectance parasitoid webs embody information
only about the presence or absence of an interaction, while quantitat
ive parasitoid webs include information about the relative densities o
f all species. 2. Connectance and quantitative parasitoid webs are des
cribed for a community of leaf-mining insects and their parasitoids in
regrowth tropical dry forest in Costa Rica. The webs were centred on
a study site that contained 88 species of plants, 92 species of leaf m
iners and 93 species of parasitoids. 3. An average of 1.22 species of
miner were found per species of plant, with more species on monocots t
han on plants with other growth forms. Leaf-miners were highly host-sp
ecific. 4. An average of 32% mortality of leaf-miners was caused by pa
rasitoids; dipteran miners were more heavily attacked than lepidoptera
n species, with coleopteran miners the least attacked. The number of p
arasitoid species per host was strongly influenced by sample size with
no evidence of an asymptote as sample size increased. Host breadth of
parasitoid species was strongly influenced by mode of parasitism (ect
oparasitism versus endoparasitism). 5. The parasitoid web did not appe
ar to be compartmentalized. Examination of the quantitative web sugges
ted that a number of different forms of indirect interaction between h
ost species may occur. There was also evidence that some species in th
e web may have a major influence on system dynamics by virtue of their
numerical preponderance.