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Re: [Live-foods] Live-Foods Digest, Vol 45, Issue 1
Some books may indeed call dragonfly larvae water scorpions, but the couple of genera of water scorpions are different insects. The water scorpions are also ambush predators. They inject digestive enzymes into their prey and then drain them (sort of like some credit card companies and time share outfits.) I was surprised to find that they are air breathers and can fly from wet place to wet place when the need arises (somewhat like backswimmers.).
Their presence with small fish or in a Daphnia culture would not be a good thing either.
If one keeps their outdoor Daphnia cultures (have a backup or backups, something will always happen to just one culture) in the shade, most larger airborne, predatory insects will not see a reflection and stop to lay eggs or settle in. The shade also (usually) keeps the food cultures from overheating and suffocating the Daphnia.
Mosquitoes and the gnats of bloodworms will still find Daphnia cultures. If one harvests at night with shallow sweeps, many of the mosquitoes can be removed, while most Daphnia are deeper in the water. One can also take out the mosquito egg rafts (they look like someone's fingernail scraped some charcoal). I put a couple eggs rafts in with small fry. The 80 to 120 or so newly hatched mosquitoes are smaller and softer than newly hatched baby brine shrimp and are usually eaten as they hatch.. Still look to see than none escape the fry and be prepared to catch the survivor and feed it to someone bigger.
Also Daphnia are opportunistic filter feeders. I've seen individuals left in fry containers to "polish the water" and clean up bacteria in there. After the fry were fed newly hatched baby brine shrimp. the Daphnia's bellies began to take on an orange hue. If they can take newly hatched bbs, they can take newly hatched mosquito larvae. Returning the Daphnia to the culture (and keeping the gnat larvae) until the population density is great enough that almost all of the mosquito larvae are consumed by the Daphnia may limit the number of mosquitoes growing up in an outdoor food culture.
In late July or August another gnat larvae shows up in the cultures. These are glassworms. They keep well refrigerated and are great food for adult killies, livebearers, Anabantids, rainbows and the like. However they are voracious predators on a small scale and after seeing what a glassworm will do to mosquito larvae, I wouldn't put them anywhere near to small fry!
All the best!
"Ray Ravary,Jr. P.C." <rravary at provide_net> wrote: Chuck,
Dragonfly larva are predatory and voracious. They attack and consume
anything they can get their hands on. I'm surprised they are getting
fish that size but it is possible. I think they are called water
scorpions in some guide books. They are at the top of the aquatic insect
food chain and do not limit their diet only to other insects. Are you
finding any corpses in your tank?
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