Here is a series of silicified--replaced by the mineral chalcedony (silicon dioxide)--midge pupae from the middle Miocene Barstow Formation, Mojave Desert, California. For perspective, the pupa at far right, in the upper row, is 4 millimeter long (about a sixth of an inch). Scientifically, it's called Dasyhelea australis antiqua. This particular species of midge, interestingly enough, is most closely related to the modern Dasyhelea australis australis, now living on the islands of Islas Juan Fernandez, about 400 miles west of Santiago, Chile.

Adult midges of the genus Dasyhelea, by the way, while often referred to as "biting midges," do not actually suck the blood of animals. They thrive by ingesting the nectar from flowers.

After dissolving the insects out of calcium carbonate (limestone) concretions with a diluted solution of formic acid, I photographed them with a Nikon CoolPix 995 digital camera in indirect lighting, with a flash unit.

Three silicified--replaced by the mineral chalcedony (silicon dioxide)--predacious water beetle larvae (a "water tiger"), called scientifically Shistomerus californense. They're from the middle Miocene Barstow Formation, Mojave Desert, California, and they're roughly 17 million years old. Such water beetle larvae are among the three dominants in the Barstow arthropod fauna--midge pupae and fairy shrimp remains are the other two. This specific variety of diving water beetle most closely resembles the living Deronectes striatellus, which is widely distributed throughout the southwestern United States.

For perspective, specimen in the middle is 6 millimeters long (roughly a fourth of an inch). Also, specimens at left and in the middle are oriented with the head toward the top, tail at bottom; water beetle larva at far right lies in the opposite orientation--head is facing toward the bottom of image. The fossil in middle is actually very well preserved, a fully mature predacious water beetle larvae, with its legs tucked against the segmented thorax; it was almost developed enough to leave the water and create a cavity (entomologists call this a cell) in the shoreline muds, transforming into a pupa, then an adult, before its death in a Miocene lake some 17 million years ago.

After dissolving the insects out of calcium carbonate (limestone) concretions with a diluted solution of formic acid, I photographed them with a Nikon CoolPix 995 digital camera in indirect lighting, with a flash unit.

A group of fossil midge pupae I dissolved out of calcium carbonate (limestone) concretions--collected from the middle Miocene Barstow Formation--with a diluted solution of formic acid (roughly 5 parts water per one part acid). They're approximately 17 million years, called scientifically Dasyhelea australis antiqua. For perspective, the specimen at far left edge of image, in the middle (with brownish stain in its center), is 4 millimeters long (approximately a sixth of an inch). This particular species of fossil midge is actually most closely related to the modern Dasyhelea australis australis, now living on the islands of Islas Juan Fernandez, about 400 miles west of Santiago, Chile.

Adult midges of the genus Dasyhelea, by the way, while often referred to as "biting midges," do not actually suck the blood of animals. They thrive by ingesting the nectar from flowers.

After dissolving the insects out of calcium carbonate (limestone) concretions with a diluted solution of formic acid, I photographed them with a Nikon CoolPix 995 digital camera in indirect lighting, with a flash unit.