Who is the baddest arthropod in the pond?
We often read descriptions of odonate nymphs as being voracious predators stalking the pond bottom and vegetated areas and possibly spreading "fear" among the various small denizens that could be prey. From some recent posts this may also include other odonates.
However the photograph above of a large dragonfly nymph (maybe Anax?) that was captured by a far smaller fishing spider (likely Dolomedes triton) indicates that spiders rule in this case. However the water tiger (Dytiscid beetle larvae) seen lurking in the photo to the right is also a powerful contender for the title as ruler of the tiny world of macroscopic pond life. Possibly the spider is fortunate that it lives mainly at the interface of the water and air and the water tiger only comes up to breathe and mainly hunts below the surface. However maybe a fight between the fishing spider and the tiger would be something worth watching? I think the outcome would hinge on who got their fangs into the opponent first.
I will admit this meeting of three arthropod predators was a setup in a plastic bowl after I netted them from one of our eight farm ponds. Does the spider ever capture odonate nymphs in nature? I do not know but it is fairly efficient at catching small fish and tadpoles or anything else that can be found near the surface. The spider certainly did not hesitate to grab this relatively enormous prey and apparently had no difficulty overpowering it.
Bill Dunson
Galax, VA & Englewood, FL
A tiny legume destroyer- the Genista moth
Another one of those things that go on in our backyards without much notice is the occasional destruction of plant leaves by small caterpillars. Sometimes we get annoyed by this and spray the plants or try to figure out what is happening. In recent walks in scrub habitat at Lemon Bay Preserve I have noticed that many of the beautiful sky blue lupines, which are not yet in bloom, are being heavily damaged by a small caterpillar (see photo attached). I was unfamiliar with this species and searched the web to find out that it is well known as a destroyer of various legumes, including lupine and members of the genus Sophora which includes necklace pod in Florida.
The rest of the story is that this caterpillar is immune to the powerful toxins found in legumes, and indeed uses these poisons to defend itself against attacks by predators. If this reminds you of some other famous cases think about monarchs and milkweeds, and zebra butterflies and passion-vines. So here is another case of a larval insect stage making itself toxic by eating a poisonous plant. Consider what this means- that the ability to tolerate the toxins must have evolved over a very long period, and then coloration advertising the toxicity (aposematic or warning coloration) developed. Then predators must recognize the significance of the warning coloration, perhaps specifically or generically. Some predators such as lynx spiders apparently can handle the toxins and eat the caterpillars
Now the adult is distinctively colored (see photo from web) but I do not know if it is protected also.
So if we needed reminding that the natural world is amazingly complex and interesting, here is another case. The deeper we look the more we see, and the more impressive the web of life becomes. So get out there and groove on nature but don't eat the caterpillars!
-Bill Dunson, Englewood, FL