From an internet source I found an image of the repulsive "berne" like the one I watched being extracted from a cow. I must have been five or six years old at the time but I could never forget the popping sound when it dropped on the ground. The adult reaction was equally stunning. 
I read that the botfly is not a fly,but the actual "berne" (the larva in its pod). The fly linked to it is "Dermatobia hominis" and one of its names in English is "bluebottle."*
Isn't it strange that in either SO or SM Nabokov mentions that his father's favorite flower is also named "bluebottle" ( cornflower)? 
*-I think this information is imprecise. I remember that because the bluebottles are very big, they lay their eggs on an emissary, a smaller fly named, then, "botfly." who transports them to their host.   
wiki-help: Bluebottle
From Wikipedia, the free encyclopedia
Bluebottle can mean:
Blow-flies (Calliphoridae) of genus Calliphora and similar species from other genera, specifically, the Blue bottle fly (Calliphora vomitoria)
Cornflower (Centaurea cyanus)
Portuguese Man o' War (Physalia physalis), stinging marine siphonophores resembling jellyfish
Blue ant, a species of large solitary parasitic wasp
See the images ( I hope I manage to include them below)
BotFly não é a mosca, Botfly é o Berne, como é conhecido no Brasil, em estágio larval.

A mosca é a "Dermatobia hominis", popularmente conhecida no Brasil como "mosca-varejeira".Bot Fly Larvae (imnowl) Tags: macro southamerica muscle tissue medical surgical larvae specimen parasite pathology maggot botflyA Bluebottle Fly ? (*Yueh-Hua 2010) Tags: flowers macro insect taiwan micro taipei  canonpowershots2is    whiteframe botfly verticalphotograph32 2006april nangangpark verticalphotograph
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