If you're looking for military SF then any of the following are a good bit:
The Serrano Series
-A period Royal Navy style Fleet and how one ex-officer interacts with the political manouvering of the families that run settled space. Good but be prepared to wade through a lot of stuff about the technical aspects of horse riding in the first book.
As I understand it, anything by David Weber
The War against the Chtorr trilogy by David Gerrold
May be very difficult to find now but incredibly good. We lose, in the first fifty pages, basically, as an alien race start terra-forming the planet.
Not quite bug hunt but huge fun (And now free on Project Gutenberg) is Space Prison by Tom Godwin.
CJ Cherryh's Fleet books are also well worth a look (RimRunners I remember as being particularly good)
There's also a fantastic series about a war with huge, fish-like aliens that are their own ships. For the life of me I can't remember the titles or authors, I'll find out and post it tomorrow.
Also also, whilst it's not military SF the Sector General books by James White touch on the field. Fascinating stories about the only cross-species hospital. Think ER with extra gravity. And limbs. And teeth...