Friday, March 4, 2011

M is for March, and Maggots

I'm sure I don't need to start this by saying I haven't been purposefully neglecting this blog, I really am rather busy. Truly, honestly. But, since I feel so badly about not writing as regularly as I had hoped 3 months ago, I'll make it up by writing about one of my favorite subjects to talk about on a first (and usually last) date.

When you say "fly" to the average person, they usually think about the common house fly, or possibly a unicorn soaring elegantly over a pastel rainbow. Yet, when I think of flies, the first thing that pops into my head is the Botfly. Why? Because its disgusting and amazing.

Botflies are particularly special, because their larvae live as parasites during their development and maturation process. Why would you want to mature in the vast world of exposed nature when you have the opportunity to embed in the flesh of another living species?

Let's break down the amazing lifecycle of the botfly, because its rather unheard of for flies to deposit their eggs anywhere other than...well, you generally only hear of maggots and fly eggs/larvae around garbage cans and dead things, right? These flies are bold, and think that their larvae deserve a better environment than a trashcan. The female botfly, a large and dominating specimen, carries the eggs. She waits until she sees a suitable intermediate vector flying around a suitable host, such as a tick near a grazing animal or a mosquito that is preparing to feast on a human. Once the female botfly has chosen her target, she tackles the insect mid-flight. They begin to fall and roll, and as this happens, the female botfly deposits her eggs onto the intermediate vector and flies away.

I know, this sounds weird, and it definitely is, but the botfly species is smart for doing this. Most species recognize the large botfly as a threat, and will avoid any contact. Yet, if the eggs are disguised on another, much smaller species, then everyone wins!

So now, we've got the intermediate vector covered in eggs. It regains flight and goes after its bloodmeal (although, not all intermediate vectors for the botfly consume blood). When the intermediate vector lands on the mammalian host, the eggs are attracted to the heat, causing them to drop and land on the flesh of their new host. The intermediate vector takes a meal close to the location of the eggs, and they burrow towards the new opening in the flesh.

Once inside, they make their way to a comfortable area under the skin and develop for approximately 8 weeks. They survive subcutaneously by breathing through small tubes in their butt that open at the surface of the skin. These are visible, and will bubble if held underwater.

When the larvae is ready to emerge as a pupae and continue developing in the wild, it will burst from the flesh of it's host. If you can stomach it, here is a video:



Botfly larvae have a distinct "hook" mechanism that allows them to attach to the layers of the skin and avoid being pulled out. If you have a botfly infestation, they must be removed with minor surgery or suffocated before removal. You can see the hooks in these photos, they are clearly visible as the darker spots that form rings around the body.






And here is an awesome photo of a dead (suffocated) botfly larvae being removed from someone's head:




Botflies can be a large issue for small farms raising animals, and for stables holding horses. Also, if the wound is licked, possibly by the animal itself (we've all seen dogs lick their wounds), then the larvae can burrow in the intestinal tract and cause severe infections.


There are many different species of botflies, and they are found all over the world, including in the United States. Now that the weather is going to start warming, you can think of this every time you leave the house!

Happy Spring!

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