How do I know if within is mold surrounded by my house? My house was built within the 60's or the 70's. I...

My house was built within the 60's or the 70's. I rent and its a one story house, pretty small. I want to know what causes the mold and how will I know if I enjoy mold in my house? My husband say that we have no insulation surrounded by the walls (one day I kicked a hole within the wall and there be no insulation) but I thought all houses hold insulation. WHere can the mold form? Since I dont own this house I dont want to tear down walls or tiles, etc. So what are the ways to report if I have mold?
Answers:    1) not adjectives houses have insulation - nearby are Fed rules that have be around for a while, but yours is older than that
2) is your house on a crawl space? does it own ventilation? if, the moisture may be 'seeping' up inside the walls since it has nowhere else to run; inside the walls is the usual place for mold because...... you guessed it - you'd see it otherwise.
Odor, mystery illnesses, discoloration are the usual signs.
in the first two, you may own to hire an inspector to use Mold detection equipment (yup, there is really is such stuff) to find it.
If you own mold it ought to be pretty obvious simply bye looking at it. If its in the walls when you kicked a hole contained by the wall you should have looked inside of it. Duh