Toxic Black Mold Identification

This information brought to you by A Accredited Mold Inspection Service, Inc. Providing toxic black mold inspections in all of South Florida from Vero Beach to the Keys since 2003.

The best way to identify if the black mold in your home is Stachybotrys, also know as toxic mold or toxic black mold is to have an inspection conducted and samples taken.

Generalized descriptions of this common fungus and it’s growth habits are as follows:

The mold is obviously very dark black in color, it often exhibits a circular growth pattern, forming round colonies of about 1 cm to 20 cm across approximately.

Sometimes the circles are complete as in the small photo at the bottom of the page. Other times, the circles are incomplete and form semi circles or crescent moon shapes when one side of the colony grows but the other side does not, possibly due to a lack of moisture or competition with other mold types.

Also, the mold often forms concentric circles of one circle inside another circle as shown in the photo. I know of no other mold that grows like this outside of the lab.

Unfortunately the above descriptions do not always apply, because over time the colonies grow together and become irregular shaped blotchy patches of dark black mold that can be confused with Aspergillus niger and sometimes even Cladosporium mold. The bottom photo shows Stachybotrys in a petri dish, above it is it’s concentric circle form, above that more circles on a bank wall in a 20,000 sf North West Florida bank we inspected, and above that is a photo of toxic black mold in Lake Worth during our inspection of a entire apartment building one year after hurricane Francis damage.

Stachybotrys is a very dark black mold; it is often reported to be shiny or slimy in appearance, however, from personal experience, this is only true when the mold is wet. It is wet most of the time because it requires very wet surfaces for growth. When it is dry, it can be powdery.

Stachybotrys or black mold grows in areas where material have been very wet for an extended period of time, such as many weeks or a few months as opposed to a few weeks or days.

Stachybotrys requires a high-cellulose, low-nitrogen food source, such as paper.

I have seen thousands of Stachybotrys colonies on inspections. I have notices that in accordance with it’s requirements for cellulose it seems to never grow on the exterior of interior of air conditioning AC ducts, nor on the interior or exterior of AC units like Cladosporium. Molds like Cladosporium and Pen / Asp are much more flexible in feeding habits. Cladosporium will be quite happy to feed off the dust inside AC ducts and AC units.
Stachybotrys black mold seems to love dark places such as the interior of wet wall cavities, or the bottom of carpets. In fact it’s most common habitats in homes appears to be on the surface of drywall materials or inside drywall wall cavities. When it grows on drywall, it is actually growing on the thin cellulose rich paper that coats both surfaces of the drywall.
The photo at the bottom left corner of this page is of a very typical “text book example” of the growth pattern of black mold or Stachybotrys. The photo is a lab stock photo of mold, however the descriptions did not come from a textbook or lab, but from this inspectors personal experiences.

Stachybotrys spores 1

Black mold or Stachybotrys spores as viewed under the microscope.
stachybotrys 11-3-05
Black mold found during mold testing in
Lake Worth.
stachybotrys in N.W. Florida
A server infestation of toxic black mold we found hidden inside every single wall in a fifty thousand square foot commercial building in the Florida panhandle.
stachybotrys bullseye
Bullseye pattern of mold found sometimes in the field is seen of a coloney of Stachybotrys grown on paper in the lab.

stachybotrys in petri dish
Stachybotrys or toxic black mold growing on agar in a petri dish in a labratory, note that it is fuzzy with white fibers and appears nothing like the same mold when found on the walls of water damaged homes and offices.

About A Accredited Mold Inspection Service, Inc.
We are certified mold inspectors providing toxic black mold testing for homeowners, renters, and commercial office building managers from West Palm Beach to Miami Florida and beyond including Lake Worth. We also find and diagnose moisture and humidity problems that are the original cause and origin of mold problems. Because without diagnosing the cause, the cure will not last.

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