Sex Ratios of Fleas (Siphonaptera: Ceratophyllidae) in Nests of TreeSwallows (Passeriformes: Hirundinidae) Exposed toDifferent Chemicals Written by PoB, verified by Editorial Team December 27, 2011 Hirundinidae, PasseriformesTree Swallow (Tachycineta bicolor) Science Article 5 abstractEndocrine disruptors have well-known effects on vertebrate population sex ratios, buta variety of chemicals can also affect sex ratios of invertebrates. We tested whether sex ratios of