If that were possible then you'd expect to see landfills teaming with beetles already. As that isn't mentioned, perhaps something else in the landfill stops them?
Though I swear they were well coordinated...
[1] http://whatcom.wsu.edu/ag/compost/fundamentals/biology_anaer...
Admittedly, that is being a bit pedantic, the question would still seem to hold if you were talking about traditional waste dumps, I have no idea about the environmental makeup of those. Although my understanding is that the number of dumps, in the U.S. at least, has dramatically decreased of the last few decades.