UA logo Allergy and Asthma in the
Southwestern United States
Information for patients with allergy and related problems
in the Southwest

Environment and allergic disease


Indoor Allergens - House Dust Mites and Cockroaches 

House dust mites 

  • These are microscopic creatures found in house dust: excreta and dead bodies of mites are important, highly allergenic triggers for asthma. 
  • They feed on human skin scales and live in mattresses, pillows, bedding and bedroom carpet. 
  • They are found in lower numbers in upholstered furniture of living rooms.
  • The most common species in the southwest is Dermatophagoides farinae (picture).    Dermatophagoides pteronyssinus is less common in the southwest of USA but is the most prevalent species elsewhere including the UK and Europe .
  • Evaporative cooling can increase indoor humidity to over 70%, and favor mite proliferation. 


  • Cockroaches are found universally, but are less of a problem in southwestern cities, as compared with inner urban areas of large cities elsewhere.   Allergy to cockroach may trigger asthma. 
  • The German Cockroach (Blatella germanica) and the Brown-banded Cockroach (Supella longipalpa) are the most common types seen in houses in Southern Arizona.  The very large American Cockroach is uncommon inside homes. 
  • Cockroaches often breed in bathroom and kitchen drains.  They are less common in houses in which kitchens and utensils are kept clean, food is properly contained, garbage is taken out daily, and food is consumed only in clean dining areas.  Eating in bedrooms increases risk of cockroach allergy.

Additional information on limiting exposure to avoidable allergens in the home to reduce symptoms of asthma and allergic rhinitis (see Limiting Exposure to Allergens in the Home). 

Further Reading on house dust, mites and cockroaches: 
AAAAI pamphlet on indoor allergens.
Ohio State University Fact Sheet on house dust mites
University of Nebraska-Lincoln Extension: Cockroach Control Manual.   2nd edition, 2006.
Pictures of German cockroaches (
Pictures of American cockroaches (

Disclaimer:   This site is for educational purposes only.  Any information that you have found in this web site is not intended to replace medical care or advice given to you by your own physicians. You should consider consulting your local medical library and other web sites for additional information. 

Comments and suggestions welcome!   Email:
Content Owner:  Michael J. Schumacher, MB, FRACP, The University of Arizona

Updated 8/2010