a filtration aid, to increase flow rate, and filter very fine particles that would otherwise pass through or clog filter paper. It is also used to filter water, particularly in the drinking water treatment process and in fish tanks, and other liquids, such as beer and wine. It can also filter syrups, sugar, and honey without removing or altering their color, taste, or nutritional properties. Abrasive The oldest use of diatomite is as a very mild abrasive and has been used in toothpaste, metal polishes, and some facial scrubs. Pest control Diatomite is of value as an insecticide because of its abrasive and physico-sorptive properties. The fine powder adsorbs lipids from the waxy outer layer of the exoskeletons of many species of insects; this layer acts as a barrier that resists the loss of water vapour from the insect's body. Damaging the layer increases the evaporation of water from their bodies, so that they dehydrate, often fatally. Arthropods die as a result of the water pressure deficiency, based on Fick's laws of diffusion. This also works against gastropods and is commonly employed in gardening to defeat slugs. However, since slugs inhabit humid environments, efficacy is very low. Diatomaceous earth is sometimes mixed with an attractant or other additives to increase its effectiveness. The shape of the diatoms contained in a deposit has not been proven to affect their functionality when it comes to the adsorption of lipids; however, certain applications, such as that for slugs and snails, do work best when a particularly shaped diatom is used, suggesting that lipid adsorption is not the whole story. For example, in the case of slugs and snails, large, spiny diatoms work best to lacerate the epithelium of the mollusk. Diatom shells will work to some degree on the vast majority of animals that undergo ecdysis in shedding cuticle, such as arthropods or nematodes. It also may have other effects on lophotrochozoans, such as mollusks or annelids. Medical-grade diatomite has been studied for its efficacy as a deworming agent in cattle; in both studies cited the groups being treated with diatomaceous earth did not fare any better than control groups. It is commonly used in lieu of boric acid and can be used to help control and possibly eliminate bed bugs, house dust mite, cockroach, ant, and flea infestations. Diatomaceous earth is widely applied for insect control in grain storage. In order to