I see you like close-up and macro. In an episode of The Grid, Scott Kelby & co. suggest cats/dogs and flowers should not be in your portfolio — unless you specialize in pet photography or shooting for florists. The reasoning was that pets are common and cute, and flowers are everywhere and beautiful, so if you have those photos in your portfolio, they had better be awesome photos.
You have attracted a greater following at 500px than I have. The problem with all the social sites like Flickr and 500px is that you leave a nice comment for me, and in return I leave a nice comment for you. A few social sites run contests, some offer prizes but most just offer bragging rights and the opportunity to run the next contest. Entering, and if you win, having to judge the next contest can be an eye opener. Having to pick the best three or four photos from a dozen or two really good shots can be a test. Winning several of these contests and regularly being in the top few, would be more of an indication of quality than comments in your gallery. Some of the same sites offer critiques, either you post asking for a critique or you post in a forum for critiques, depending on the site. Anyone can give a critique and while any critique may be valid, I prefer those giving critiques have a gallery so you can see their work, that way you can add weight to the critique based on what you think of their work.
Your gallery doesn’t inspire me, but it holds promise. A photo like http://500px.com/photo/11512341 shows you can manage your camera well. It’s too bad the tips of the green parts have died and decayed, but the really bright yellow, green underside and background are handled pretty well.
Your fly has bad lighting and a too shallow depth of field. EXIF data says it was shot at ISO 100, you could have increased ISO to some value before noise really becomes troublesome then stopped down your lens for more depth of field while maintaining shutter speed. Flash or a reflector would have helped the lighting. I know, flies are a pain, you get too close and they leave. I suppose that is part of the challenge. If you really want to be challenged, try taking bees, butterflies and dragon flies while in flight.
Although he died of ALS in May of 2011, Ronnie Gaubert had one of the best galleries of bugs and plants I know of. He was strictly amateur and is one of the best arguments for not equating amateur with low quality. Fortunately, his family has maintained his site in his honour. It is here: http://www.pbase.com/ronnie_14187/the_nature_of_louisiana_2005, and if you are interested in macro and nature photos, it is well worth the time to look.
My web page has flowers and bugs but is much more general in nature as I will shoot almost anything, anywhere. There is a link on the Photography Showcase forum here. If you are interested, you are welcome to look, but for flora and fauna I recommend Ronnie’s page at the link above. Compare your photos, draw your own conclusions. If you have questions, ask.