Galls or cecidia are a microhabitat for many wasp species of the family Cynipoidea. Diversity and richness of wasps of the Cynipini tribe were estimated indirectly from their microhabitat (gall). We also inferred the relationship between galls and environmental factors in the temperate forest of Sierra Fria, Aguascalientes. Ten sites were sampled; two permanent plots 50 × 50 m were established and sampled in rainy and dry seasons at every site. In each plot, presence, and abundance of galls in oaks were quantified, as well as weather and geographical data. Richness and alfa (Hill series) and beta (βtotal, βrepl, and βrich) diversity were determined per period, site, and host level. Canonical correspondence analysis was used to evaluate effects of environmental factors on wasp richness. A total richness of 78 galls was found, which could represent 35 to 40 wasp species. Differences in abundance and diversity were found among sites, hosts, and time periods. βtotal showed variation in diversity was explained by replacement of species rather than differences in richness. Species richness and hosts were affected by weather and geographical variables. Use of galls as an indirect indication of richness and diversity, host-parasite interaction, and its environmental interaction were discussed for conservation purposes.