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For excellence in biological observations of insects, the studies recorded in the following pages are unsurpassed. "Trap-nesting Wasps and Bees: Life Histories, Nests, and Associates" is a model of scientific achievement which should be carefully examined and emulated by aspiring young students. Over a period of a dozen years the naturalist-entomologist Dr. Karl V. Krombein has pursued his investigations with persistence, perspicacity, and care. The purposes of his work are manifold, but high in priority has been his consuming desire to stimulate and encourage the ecological approach to the study of taxonomy.
The information presented in this report embraces the study of many thousands of individual wasps, bees, beetles, and mites obtained from more than 3,400 trap-nests, representing nestings of 75 different predaceous wasps, 43 nonparasitic bees, and 83 parasites and predators associated with them. No such extensive material, yielding so much important, new data, has ever been accumulated on the subject.
Dr. Krombein's technique of studying trap-nests is not new, but he has greatly expanded its use to make possible the acquisition of many new data. Had the investigator not been encumbered by the necessity of engaging in tedious, but necessary, routine detail even more highly significant results might have been obtained.
No effort was spared to examine and record the nature of the architecture of the nests, competition, correlation of cell size and sex, prey, and other features of the fascinating and complicated life histories of these insects. Thus, many lacunae in our knowledge of these animals have been filled. For example, Dr. Krombein has shown (1) that in 100 nests of 6 to 9 cells, each cell provisioned with an average of 23 spiders, more than 20,000 prey were used by the sphecid Trypargilum t. tridentatum and (2) that 20,000 caterpillars of a single species of olethreutid moth were used to provision 250 nests of a Floridian vespid! The enormous pressure exerted on the populations of the two prey species has been clearly and convincingly demonstrated by these examples.
Among the many "firsts" disclosed in the following pages are the discovery that a certain megachilid bee constructed a brood chamber instead of a series of cells containing only one egg in each, the discovery that certain forms, previously considered discrete subspecies, are actually only color phases of one, and numerous facts concerning behavior and host associations of parasites and predators.
Abundant information is given on the trap-nesting technique and the methods of nest study. The author is explicit, leaving no doubt as to what should be done by those who wish to engage in similar investigations.
J. F. Gates Clarke, Senior Scientist
Department of Entomology
Museum of Natural History
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Posted August 6, 2009