Template Error: no appropriate default constructor available

1>  ecosystem.cpp
1>c:program files (x86)microsoft visual studio 10.0vcincludemap(172): error C2512: 'beatle::beatle' : no appropriate default constructor available
1>          c:program files (x86)microsoft visual studio 10.0vcincludemap(165) : while compiling class template member function 'beatle &std::map<_Kty,_Ty>::operator [](int &&)'
1>          with
1>          [
1>              _Kty=tokenID,
1>              _Ty=beatle
1>          ]
1>          c:userszakdocumentsvisual studio 2010projectsascii_sivvureascii_sivvureecosystem.h(22) : see reference to class template instantiation 'std::map<_Kty,_Ty>' being compiled
1>          with
1>          [
1>              _Kty=tokenID,
1>              _Ty=beatle
1>          ]

typedef std::map<tokenID,beatle>    Beatles;

class ecosystem
{
private:
line 22:    Beatles m_Beatles;
};

ecosystem::ecosystem(): m_output( output() )
{
    Beatles m_Beatles;
}

void ecosystem::populate()
{
    if (m_isMatingSeason && ( random(0,1000) < rateMATING ) )
    {
        beatle babyBeatle = breed();
        m_Beatles[babyBeatle.getTokenID()] = babyBeatle;
        m_field.occupy(babyBeatle.getTokenID(), babyBeatle.getLocation() );
    }
}

m_Beatles[babyBeatle.getTokenID()] = babyBeatle;