Giant Water Bug

Description:

Large, aquatic true bug, about 25mm long. Raptorial forelegs (used for grabbing prey), broad flat mid and hind legs. Oval in shape with small head with a long, pointed piercing-sucking mouthpart extending off the from and large eyes on either side. Two small rounded projections extend off the back end of the bug, used in respiration. These are very small for this species and they are larger in nearly every stream nearby.

Habitat:

Found at Las Cienegas, a spring-fed riparian area north of Sonoita, Arizona. The stream is very clear, usually cool, and nutrient rich. Full of watercress and duckweed most of the year. Deep mud forms the bottom of the stream. The water flows very slowly, almost so that you can't observe the flow. The area around the stream is full of cottonwoods, cattails, and grasses, and wild mint lines the banks along most of the length. The stream is nearly always shaded along most of its length. How far downstream the water flows depends on the time of year and the water goes underground near the spring head during the dry parts of the year. On the date the bugs were observed, the stream extended some ways beyond that area. Other inhabitants of the stream include dragonfly and damselfly larvae, frogs and tadpoles, scuds/sideswimmers, aquatic beetles, and flatworms (planarians). Cattle are present near this habitat and there was evidence of a recent visit in the area when the bugs were observed.

Notes:

Giant water bugs are often the top predators in Arizona's desert streams. In this particular location, they are the top predators. Giant water bugs are excellent predators and known to capture, subdue, and consume animals much larger than they are, including vertebrates (animals with backbones). Giant water bugs are also known for their parental care behaviors. This species is a back brooder, so the females lay their eggs on the backs of the males and the males care for them until the hatch. No males with eggs were observed during my visit on May 14, 2011, but the area was crowded with people and I didn't spend as long at the site as I normally would, so I didn't see any males at all.