I've observed the Dynamic Aviation aircraft flying those patterns over LA for over a year, and while at first I thought it could be related to their surveillance operations, I'm pretty sure they're actually Sterile Insect Technique flights: http://www.dynamicaviation.com/flight-solutions-and-services...

There's a lot of info online about Dynamic Aviation doing Sterile Insect Technique flights over southern California, and their contracts to do so.

There are other spooky defense contractors doing what may be imagery collection flights, though. Like KEYW: https://twitter.com/lemonodor/status/647109884488454144