A pilot program has been launched in England to take blood samples from animals in zoos not with plastic syringes but with live, bloodsucking insects known as a kissing bugs.

You may feel a slight pinch…
As many of our zoo keeper readers can tell you, taking blood samples from animals in zoos can be a very stressful and complicated undertaking, often involving sedating the captive creatures. Through the new program first reported by the BBC and being tested now at the London and Whipsnade zoos, the keepers are…
…using kissing bugs to do their work for them. The kissing bugs are raised in a sterile environment and “administered” to the zoo animals during feeding time.
“It might take somewhere between 10 and 30 minutes to get a decent sample dependent on how hungry the bug is, how quickly it finds a blood capillary and how thick the skin of its host is,” veterinary officer Tim Bouts told BBC. Am I the only one furiously scratching myself right now as if I”m being eaten by kissing bugs? Thanks BBC! What’s that you say? You’re not scratching your body viciously like a meth addict right now? Fair enough. Maybe you should try reading this account of kissing bugs by Charles Darwin. That should do the trick:
“We crossed the Luxan, which is a river of considerable size, though its course towards the sea-coast is very imperfectly known: it is even doubtful whether, in passing over the plains, it is not evaporated and lost. We slept in the village of Luxan, which is a small place surrounded by gardens, and forms the most southern cultivated district in the Province of Mendoza; it is five leagues south of the capital. At night I experienced an attack (for it deserves no less a name) of the Benchuca, a species of Reduvius, the great black bug of the Pampas. It is most disgusting to feel soft wingless insects, about an inch long, crawling over one’s body. Before sucking they are quite thin, but afterwards they become round and bloated with blood, and in this state are easily crushed. One which I caught at Iquique, (for they are found in Chile and Peru,) was very empty. When placed on a table, and though surrounded by people, if a finger was presented, the bold insect would immediately protrude its sucker, make a charge, and if allowed, draw blood. No pain was caused by the wound. It was curious to watch its body during the act of sucking, as in less than ten minutes it changed from being as flat as a wafer to a globular form. This one feast, for which the benchuca was indebted to one of the officers, kept it fat during four whole months; but, after the first fortnight, it was quite ready to have another suck.” — Note: Luxan is Luján de Cuyo.

Vets take a blood sample from a manatee at a Tampa’s Lowry Park Zoo.
Kissing bugs administer a “pain reducing enzyme” as they bite their prey, so the animals do not seem to feel anything. Once the samples have been collected the bugs are then humanely killed and the blood is harvested by the keepers. The animals don’t go through the stress of sedation; the keepers get their blood without the hassle; and the kissing bugs get one last meal before their are systematically murdered and disemboweled. I just don’t see a downside for any of the parties involved.