Here are a few photographs of kleptoparasitic flies stealing hemolymph from a praying mantis dining on a pentatomid. They might be Milichiella arcuata or M. lacteipennis, types of jackal flies, but those are just guesses. Jackal flies (Milichiidae) and frit flies (Chloropidae) are commonly found on dead insects, but the volatiles released by dismembered true bugs are apparently especially attractive (see Zhang and Aldrich 2004). And if you search online for images of jackal flies, they also seem to be common on dead or dying honeybees, so presumably bees exude a volatile that is attractive to flies as well. I’d love to find an article that times the arrival of various kleptoparasitic flies at different types of insects … could use the assemblages to give approximate time of death, I’m sure, just like on CSI. I don’t watch CSI, so I’m guessing here as well.
Tag Archives: diptera
Now that everyone wants to kill mosquitoes that transmit Zika virus, can somebody please make a transgenic plant that expresses mosquitocidal Bti (Bacillus thuringiensis subsp. israelensis) toxins? Just stick the Bti gene behind a phloem-specific promoter so that the protein gets pumped into the nectar. Then when males and female mosquitoes drink (and almost all do), they die. You could then plant acres of the modified plant nearby towns to protect people from Zika (and anything else transmitted by mosquitoes). The beauty of this method is that you could reduce populations of mosquitoes from an area without spraying, and do so for generations if you modified nectar-producing perennials. I know it’s trendy to dislike GMOs (like vaccines), but I think many people would support them under these circumstances.
And yes, apparently Bti toxins can kill adult mosquitoes (including Aedes aegypti), not just larvae. Klowden and Bulla 1984 demonstrated it, for example. And yes, Aedes aegypti drinks nectar (and probably fruit juice).
Of course, even if somebody had the incentive to make such a plant, it could take a decade to wade through the red tape involved in getting non-regulated status from governments. So if you want to do something today, leave out containers of sugar water (10%) that is laced with Bti (e.g., Mosquito Dunks, which you can buy online or at hardware stores). Maybe add something floral to attract them, too. (A review of olfactory cues suggests that imitation cherry and apple can work. If you don’t have those sitting around, I’d wager a few drops of jasmine flavoring or rose water would work, and those are easily found at local stores.) Even if the Bti doesn’t immediately kill the adult, adults sucking up a big sugar meal can transfer the bacteria to water where they lay eggs, and thus eventually cause the death of any larvae that develop. Note that bees and ants might get interested in your sugar water, but the Bti is completely harmless to them.
And if you don’t want to use Bti, there are plenty of articles on using sugar baits laced with insecticides (e.g., Qualis et al. 2013, Junilla et al. 2015). They really can work: mosquitoes absolutely love sugar and will drink up poisons in the process. These are great if you don’t want to use crop dusters to destroy all insects in the area.
If you have kids and want to entertain them, add food dyes to the sugar bait and then challenge them to find mosquitoes with bellies full of sugar water. For older kids that might be amused by actual science, use two dyes to test attractiveness of two different volatiles (or different sugars). It’s probably rare to recapture one right after a nectar meal, but when distended they reveal gut contents nicely.
FYI, the photograph above is a white-footed woods mosquito (Psorophora ferox), not Aedes aegypti. It doesn’t transmit Zika, but illustrates to the unbelieving that mosquitoes drink nectar.
This golden-backed snipe fly (Chrysopilus thoracicus) landed in one of my bird baths and drifted around for a few minutes on the surface tension. I’m not positive, but I think I’ve seen them do this in past years, too. I wonder whether they are looking for mosquito larvae, or perhaps adults. These flies have predaceous mouthparts, so they clearly hunt something. Sure wish somebody would PCR the gut contents of these things and let me know. Anyone ever seen them take something down?
Here’s another one, albeit one with a damaged eye:
Just a silly little graphic I made for a friend coordinating a blood drive … with the idea that a sticker might be made for donors:
I also wrote a silly little blurb, though I’m sure the math could be improved upon:
“Some people might be hesitant to donate blood if they haven’t done it before, so I just wanted to remind everyone that they have, indeed, donated blood before: to mosquitoes. A typical mosquito (always a female, by the way) flies away with 0.001994 mL per meal, at least according to an article from 1937 on blood loss in horses. Not so much, perhaps, but it adds up when her friends find you, too, and they do. So you’ll donate a pint of blood after being visited by 237,212 of the little beasties. Much easier to just sign up and be done with it in 10 minutes. And it won’t itch when you are done!”
Three more photographs from my trip to Oregon, for those who like robber flies. I just love these beasties.