As a kid I would have spent all my time catching frogs, snakes, & turtles and would have mostly ignored the spiders, moths & butterflies. The species list is from Massachusetts Wildlife, No. 2, 2009 Field Guide to the Reptiles of Massachusetts. Italicized entries are not found in Middlesex County.
Chrysemys picta (Painted turtle) (Whipple Hill, 8/18/02 11am)
Pseudemys rubriventris (Nothern Red-bellied Cooter, endangered)
Clemmys guttata (Spotted Turtle, protected)
Glyptemys muhlenbergii (Bog Turtle, endangered)
Glyptemys insculpta (Wood Turtle, special concern)
Emydoidea blandingii (Blanding's Turtle, threatened)
Malaclemys terrapin (Diamond-backed Terrapin, threatened)
Terrapene carolina (Eastern Box Turtle, special concern)
Trachemys scripta elegans (Red-eared Slider) Native to the Mississippi River watershed.
Sternotherus odoratus (Eastern Musk Turtle)
Chelydra serpentina (Snapping Turtle) (Parker Meadow, 7/1/12 1pm, 8/2/2014 4pm) I have seen several crossing roads, some successfully, others not, but I've never had a camera handy at the time. My whole baseball team got an excellent look at one as it strolled all the way across the outfield during a game at the Harrington field. Again, no camera.
Coluber constrictor (Black Racer, North American Racer) (Upper Vine Brook path, 4/03) I actually didn't see it, but my wife did and called me on my cell phone. I ran to the bike path, but before I could get there a little girl ran over the snake with her bicycle. The wounded snake disappeared into the woods.
Carphophis amoenus (Eastern Wormsnake, threatened)
Diadophis punctatus (Ring-necked Snake)
Pantherophis alleghaniensis (Eastern Ratsnake, endangered)
Heterodon platirhinos (Eastern Hog-nosed Snake, protected)
Lampropeltis triangulum (Milk snake) (Willards Woods, 6/13/09 12pm, 6/1/13 10am)
Nerodia sipedon (Northern Watersnake)
Opheodrys vernalis (Smooth Greensnake)
juvenile mating Thamnophis sirtalis (Common garter snake) (Whipple Hill, 9/23/07 12pm, Lower Vine Brook, 10/8/11 3pm, mating 4/12/14 11am) The second photo is of a juvenile, only about 6-8" long. It was sunning itself on the bike path and was quite ferocious about defending its spot. It struck at my hand multiple times, but I couldn't get a photo with its mouth open. My wife and son saw one trying to eat a tufted titmouse in our back yard. It wasn't clear if it killed the titmouse itself or if it found it dead. It gave up after it could only fit the head into its mouth.
Thamnophis sauritus (Eastern Ribbonsnake)
Storeria dekayi (Dekay's Brownsnake)
Storeria occipitomaculata (Red-bellied Snake)
Agkistrodon contortrix (Copperhead, endangered)
Crotalus horridus (Timber Rattlesnake, endangered)