Racial differences also exist in the cerumen glands, apocrine sweat glands which produce earwax. This is referred to as excessive earwax or impacted cerumen. Blue whales secrete earwax (cerumen) throughout their lives forming long, multilayered plugs. Cerumenolytics are used to treat cerumen impaction in cats and dogs. The lubrication provided by cerumen prevents desiccation of the skin within the ear canal. Together, these two sets of glands produce natural ear wax, or cerumen. An unusually dark colored ear wax (cerumen) may also be produced. A/B otic drops is also indicated for the removal of excessive or impacted cerumen. In America 3.6% of emergency visits caused by ear issues were due to impacted cerumen. In wet-type cerumen, these lipids include cholesterol, squalene, and many long-chain fatty acids and alcohols. To construct their nests, "M. scutellaris" use cerumen, a mixture of wax and floral resins. In Brazil 8.4-13.7% of the population have impacted cerumen. They are built out of brown cerumen, and house the eggs and larvae. At night, the guards will then seal the cerumen tube entrance. Cerumen coverings, produced by workers, insulate cold spots.