|Laccophilus pictus coccinelloides, Sabino Creek, Pima Co, AZ 4-4-2012|
Note the air bubble that is held under the elytra. When the beetle has used up oxygen from the original air, fresh oxygen diffuses from the water into the bubble. It's a physical gill. From time to time fresh air needs to be collected at the surface because the bubble constantly looses nitrogen to the water, which cannot be recovered, so it keeps shrinking. The beetle does not need the nitrogen per se, but it needs to keep up the volume of the bubble to allow for the exchange of O2 and CO2 with the water. So occasionally, it comes to the surface for refills.
|Thermonectus marmoratus, Sunburst Beetle|
|Agabus disintegratus, adult and pupa|
|Large whirligig beetle, Dineutus sublineatus|
Many true bugs lead aquatic lives, and all states of their life-cycle are water-bound, even though the adults of most species are good fliers. All I can think of a predatory and administer venom and digestive juices through their pointed 'beaks', some have raptorial arms, most have legs that are adapted to swimming and diving.
|Graptocorixa (Water Boatman) Nymph|
|Gerridae, Water Striders|
|Water Scorpion Ranatra quadridentata, Madera Canyon, Sta Cruz Co, AZ|
|Larvae of Archilestes grandis (Great Spreadwing), Libellula sp. (probable Flame Skimmer), and Paltothemis lineatipes (Red Rock Skimmer) photo Bob Barber|
Other insects that spread more delicate wings once they have outgrown their aquatic larval phase, do not return to the water as adults, except to deposit their eggs.
This great photo of Odonata (Dragonflies and Damselflies) was taken in New Mexico, but all three species can be found in Arizona as well.
|Camelobaetidius larva, Sycamore Canyon, Santa Cruz County, Arizona, USA, |
March, 13 2012
|Petrophila jaliscalis, Santa Cruz River, Between Wheeler Taft Library and Ina Bridge, 11-24-2014|
Adult females enter the water to oviposit, carrying a plastron-like layer of air as a source of oxygen
The larvae are aquatic, living within a silken web in fast-flowing streams;
they scrape diatoms and other algae from rocks in streams.
Trichoptera or Caddisflies,, those hairy cousins of the scaly Lepidoptera, are obligatory aquatic breeders. Their larvae build tubes out of detritus and anker themselves on the bottom of slow moving creeks.
Corydalus texanus (Dobsonfly), Clear Creek, Yavapai Co, AZ
These are just a few examples of the rich diversity that can be found even in Arizona's creeks and ponds. More than any other habitat, these ecosystems are delicate and threatened by pollution, grazing, mining and continuous droughts.