High throughput drug screening assay methods and related apparatus are described. Wild-type Drosophila are raised in multi-well microtiter plates on a growth medium having a high level of a sugar such as glucose. The high sugar diet during development induces screenably distinct characteristics in the wild-type Drosophila. Compounds that putatively modify the screenably distinct characteristic are tested by feeding to the Drosophila embryos, and determining whether the compound modifies the screenably distinct characteristic induced by the high sugar growth medium. The assay methods and related articles of composition can also be used to assay toxicity of candidate compounds.