Usually, how long after consumption of marijuana can
delta-9-tetrahydrocannabinoe be detected in the body with testing?

blackvision...

Thank you for your question regarding Delta-9-tetrahydrocannabinol. 
Delta-9-tetrahydrocannabinol, also known as Delta-9 THC or THC, is the
active component in cannabis that creates the "high" when cannabis is
ingested.  This effect is experienced depending on the method of
ingestion with the onset being as short as a few minutes when smoked
to up to two hours when taken orally (eaten).  The actual
Delta-9-tetrahydrocannabinol is only detectable in the blood for only
a few hours after ingestion and is not found in the urine or fatty
tissue.  However, the Delta-9-tetrahydrocannabinol rapidly metabolizes
into 11-hydroxytetrahydrocannabinol (THC-OH)which are then converted
into THC-COOH and THC-DI-OH. It is these metabolites that can be
detected for a period of time after ingestion.  So, the direct answer
to your question is Delta-9-tetrahydrocannabinol is detectable for a
few hours after ingestion.  I think that your question, however, is
more along the line of how long the metabolites are detectable.

The numbers regarding the detection of THC metabolites are wide and
varied.  There are several factors involved in determining how long
these metabolites can be found in the body.  Amount ingested
(typically smoked), body weight, frequency of use and testing
equipment used all have a bearing on the results of a detection test. 
The time can range from as short as 3 days for infrequent users, to up
to 30 days for more frequent users.  However, hair testing, as opposed
to urine testing, can sometimes show traces of the metabolites for up
to 6 weeks after consumption.  From the research I have seen, it
appears the average for infrequent use is approximately 7-10 days and
for frequent users from 14-24 days.

Thanks again for your question and if you need any further
clarification, please let me know.

Regards,

-THV

Search Strategy:
delta-9-tetrahydrocannabinol detected

References:

Marijuana
http://www.coolnurse.com/marijuana.htm

How long does a drug stay in your system?
http://www.ccguide.org.uk/blood.html

Drugs in Sports: Recreational and Street Drugs - Marijuana 
http://www.drugfreesport.com/choices/drugs/street/marijuana.html

Cannabis
http://www.release.org.uk/cannab.html

General Drugs of Abuse Information: Drug Detection Testing
http://www.drugdetection.net/drug.htm

The other problem is trace indications often appear in people who have
not used any marijuana, so an honest report might say 99% confidence
that no marijuana has been ingested or 99% confidence that marijuana
has been ingested or any percentage in between.   Neil

"Delta-9-tetrahydrocannabinol, also known as Delta-9 THC or THC, is the
active component in cannabis that creates the "high" when cannabis is
ingested."

Although this is true, it is not the sole component of marijuana that
makes the user feel high. There are other cannabinoids that cause this
effect.