passing list values to an executemany cursor

Greetings,

I'm having trouble passing values (double precision) from a python list 
to the executemany cursor. I am affraid this is a terribly simple issue 
but it has stymied me completely, which reveals my very WBTE status with 
regard to python. Here is my code:

import xlrd, psycopg2
con = psycopg2.connect("dbname=fb host=localhost port=5432 user=<user> 
password=<password>")
bk = xlrd.open_workbook("<path>.xls")

cur=con.cursor()
#Named cells in an excel workbook....
frcs_names=['pmh_chainsaw','pmh_loaderb','pmh_loaders', 'pmh_truck']

frcs_o=[]
for j in frcs_names:
    cv = bk.name_map[j]
    for i in cv:
        p=(i.cell().value)
        frcs_o.append(p)

#make a dictionary for fun
fr_dict = dict(zip(frcs_names,frcs_o))
print fr_dict 


cur.execute("DROP TABLE IF EXISTS pmh")

cur.execute("CREATE TABLE pmh ()")
for i in frcs_names:
    cur.execute("ALTER TABLE pmh ADD COLUMN "+i+" double precision")
con.commit()


insert_st='INSERT INTO pmh VALUES ('+frcs_o+')'
cur.executemany(insert_st)

con.commit()
   

The result is as follows:
 >>> {'pmh_chainsaw': 84.031250000000014, 'pmh_loaderb': 
155.75707692307691, 'pmh_truck': 93.977430555555571, 'pmh_loaders': 
126.94655384615383}
Traceback (most recent call last):
  File "/tmp/py4195FHt", line 38, in <module>
    insert_st='INSERT INTO pmh VALUES ('+frcs_o+')'
TypeError: cannot concatenate 'str' and 'list' objects

It appears that the connection is working and the lists have been 
populated. I can check the db and see that the table has been created 
with the appropriate column names. Any hints on correctly passing the 
list falues from the 'frcs_o' list would be most gratefully recieved.

pt