Nest-dwelling parasites are known to have detrimental consequences for many birds, and thus it may be desirable for management practices to remove these parasites. In addition, manipulation of parasite loads is often necessary for studying host-parasite evolution. While there are various methods that are effective at reducing parasite loads in nests, many of them have shortcomings because they require specialized equipment, are time consuming, or involve toxic substances that may be dangerous to both birds and researchers. I evaluated the efficacy of simple-to-use, non-toxic diatomaceous earth (DE) at reducing ectoparasite loads in nests of Tree Swallows (Tachycineta bicolor) over two field seasons. Diatomaceous earth significantly reduced population sizes of bird fleas (Ceratophyllus idius) and various species of blow flies (Protocalliphora spp.) in both years. Diatomaceous earth appeared to be more effective at reducing the numbers of fleas, possibly because fleas have smaller body size and so are more easily desiccated by the abrasive action of DE. Although DE was effective against both fleas and blow flies, it did not completely rid nests of either type of parasite.