Answer to Case 806

Answer to Case of the Week 806: Myiasis-causing fly larva, consistent with Dermatodia hominis

As noted by Idzi, this is an "L3 larva of Dermatobia hominis. Typical are large and heavily pigmented spines that are arranged in neat rows. Also typical for L3 larvae of D. hominis is their general pyriform shape." 

Note the lack of spines on the terminal 3 segments, which is characteristic for this species. 

Definitive identification is through examination of the posterior spiracles, which are unfortunately a bit hard to see in this case. However, if you use your imagination, (and maybe squint a little bit), you can make out the 3 straight slits with just a slight curve to them, and can appreciate that they lack a peritreme:

Thankfully removal is curative. 

Some more wisdom from Idzi:

Fun knowledge fact: Dermatobia hominis flies will not deposit their eggs directly on humans but rather on a bloodfeeding insect, which will transport it to the human host during a blood meal! Therefore this type of myiasis will usually present on "exposed skin areas". In contrast, its African counterpart (Cordylobia anthropophaga) deposits its eggs usually on clothing that is drying outside, thus resulting in myiasis of usually the "unexposed" areas of the body: scalp (putting on a contaminated T-shirt), back, legs (putting on trousers),...

Thanks again to Race Rucki and Jason Shearer from the University of Vermont for donating this classic case!