There are a lot of insects--any way you want to count them. In one of classics of entomological literature, Howard Ensign Evans (1984) cites a calculation of the number of flies that might result from a single initial fertilized female in course of an average summer in Washington, DC, assuming that all survived (p. 160). That number is over 5.5 trillion, yes trillion. If you are having a hard time getting your mind around this quantity, another researcher estimates that offspring of a single pair of flies would create a mound 47 feet thick over entire surface of Germany. Thankfully, Malthus was right, at least as far as flies are concerned: limited resources and other vagaries of life keep numbers down considerably. Still, there are more than enough insect infestations as far as most of us are concerned. Insect numbers are also spectacular in other ways. Nigel Stork (2007) begins an article on insect biodiversity with rather startling statement that: To a first approximation, all multicellular species on Earth are (p. 657). He bases this assertion on fact that over half of known species belong to class Insecta, and these more than 850,000 species probably represent only 5-20% of those actually crawling earth today. Stork mentions these numbers and then adds that despite speciesdominance of insects, most explanations of terrestrial biodiversity are primarily based on birds, large mammals, and plants. He then describes two recent studies that attempt to redress this imbalance. One surveyed three groups of rainforest insects in lowland rainforests of New Guinea: those that eat wood, fruit, and foliage. This study found a low rate of change in species over territory monitored, an area about size of South Carolina. In a related study, researchers found similar host specificity in these rainforests and in temperate regions of Europe. However, a study of caterpillars in Western Hemisphere found less specificity in temperate forests. There may be several reasons for this divergence in results, including varying methodologies employed. Also, data for New World study were much more extensive and covered three quarters of a century while New Guinea data were all recent. In addition, there's possibility that these two regions are indeed different from each other, that species diversity is influenced by evolutionary history. What both studies did have in common is that they focused on herbivores and paid no attention to insects that feed on dead material, bacteria or fungi--and parasitic insects were also ignored. What portion of forest populations these other species represent is also debatable, with some estimates running as low as 16% and others as high as 50-70%. That's quite a range, and it suggests that there is an awful lot we just don't know about these ubiquitous creatures. Drosophila Genetics Even when it comes to Drosophila, there's still a great deal to learn, though they've been object of intense study for a hundred years (Kohler, 1994). They were passe as research subjects for awhile when molecular biology fell in love with bacteria. But as molecular techniques became more sophisticated, there was renewed interest in Drosophila in 1980s (Weiner, 1999). One of new leaders in field was Edward Lewis (1918-2004) who had been educated during first wave of interest in fruit flies and had never abandoned them. He was rewarded for his perseverance with Nobel Prize in 1995 for his work on homeotic genes that control segmentation in early development. There are hundreds of species in Drosophila genus and because it has already been so extensively studied it is focus of much research attention at moment. Just as rich seem to get richer, well-studied seem to get even better studied because there's such a sound foundation on which to build. It's much easier to do genomic work on species for which many genes, their locations, and products are already known. …