It was a bit chill early on so we waited until the sun came up before taking our morning walk. It was perfect weather with just a hint of the clouds that eventually built into a gray day. But we enjoyed the glorious sunshine and on returning home a strange thing on the pavement caught my eye. It looked like a little turd (or big, depending on the animal) except for the ridges. At closer inspection it was clearly a grub of some sort, and having never seen one of these before I was determined to ID it.
Here is the little bugger below. It's about an inch long and half an inch wide, a soft fleshy thing, covered with black spikes, two little pinchers at one end and two plate-like things at the other.
So long story short, after a couple hours searching the internet for grubs I turned up an exact look-alike creature called Cuterebra. A bot fly. My first thought was the burros or the horses, but no, this one is associated with our old nemesis Neotoma, the wood rat, aka packrat.
Now to go over the life cycle of the bot fly...
An adult fly lays eggs near the burrow of a wood rat or whatever rodent (a related species is associated with rabbits). The eggs attach to a passing animal (somehow they respond to body heat), hatch into the first larval stage and make entry into the animal through the mouth (when the animal licks its fur), or the nose or a wound, whereupon a migration within the body occurs, usually to just under the skin but sometimes a larvae loses its way and infects the throat, eyes or brain. (It's bad news when that happens and I won't go there now.) Then the larvae starts growing, forming a nodule under the skin with a visible pore or breathing hole. Pictures of these parasites in rodents are striking because they are so freaking big. Once maturity is reached the bugger breaks out of the skin like in a horror flick, falls to the ground and pupates in the soil where it eventually emerges as a mature adult fly ready to breed. The critter I found appears to be the break-out stage. Not sure how it got into the driveway on a chilly morning, but I thought it was a dead thing until it started squirming under the heat of the microscope light. Gross and awesome at the same time.
So, moving on from the fascinating horror of the bot fly life cycle, these critters are known to accidentally infect dogs, cats and people, giving me another thing to worry about and leaving us with yet another reason to hang steady in the never ending war with our damnably destructive packrats.
