Stachybotrys chartarum is a mold species that not uncommonly is found growing on materials containing cellulose subject to repeated wetting. Commonly infested materials include gypsum board (drywall), paper products, some textiles, and cellulose insulation.

Stachybotrys is a dark-colored mold appearing black on infested materials as it matures. It is one of a number of mold types that is darkly pigmented. If mold infested material looks black in color, it may or may not be Stachybotrys. In most cases it is not. However, one does not know the type of mold it is without looking at it under the microscope. A sample can be taken by pressing transparent sticky tape against an infested surface and transferring the tape to a microscope slide.

Stachybotrys produces large (> 10 m m long) dark spores which on maturity look like they have a very rough surface. Because the spores are large and usually sticky as they mature, Stachybotrys spores do not remain airborne for more than a few minutes. As a consequence, they are only occasionally observed when airborne mold tests are conducted in areas of infestation. Significant airborne levels generally only occur when infested materials are disturbed. As such, one should be very careful in removing black mold-infested materials unless you know it is not Stachybotrys.

Stachybotrys has garnered a lot of attention in the last couple of years as several TV news magazines including 48 Hours (just recently) have covered the issue of Stachybotrys infestation of houses and a variety of health threats it may pose on exposure (particularly to children).

Stachybotrys is toxigenic, that is it produces a number of potent mycotoxins (e.g. saratoxin H). Field investigations conducted by staff from the Centers for Disease Control (CDC)are suggestive that exposure to Stachybotrys may be the cause of hemesiderosis, a hemorrhagic disease of the lungs of infants reported in the Chicago and Cleveland areas. Hemesiderosis is a serious disease since the mortality rate is reported to be about 40%. Animal  studies indicate that Stachybotrys spore exposures can cause bleeding in the lungs and recently Stachybotrys spores have been reportedly isolated from lung tissue of hemesiderosis patients.

Exposures to Stachybotrys at relatively low levels is likely to cause immunological sensitization which results in allergy and even asthmatic-type symptoms. Adults who have disturbed Stachybotrys have been reported to have experienced respiratory problems, and skin rashes.

Stachybotrys is a potentially dangerous mold. Its presence in houses and other buildings is not that uncommon. As such, its presence, in of itself, should not be a cause for alarm. Large infestations (more than a few small spots) should, however, be taken seriously. Removal of infested material in a "safe" manner is essential. Large infestations should be removed by professionals. The major exposure risk occurs when Stachybotrys is disturbed; such disturbances may occur when Stachybotrys infestations are being remediated. The rule of thumb for removing Stachybotrys is to treat it with respect, indeed more respect than is given in asbestos abatement projects.