Soaring with the Tarantula Hawk Wasps
Tarantula hawk wasps, or more simply tarantula hawks, are a sub-group of the spider wasp family Pompilidae, famous for both their painful sting and their tendancy to predate exclusively on tarantulas and large spiders. The tarantula hawks encompass two genuses. Pepsis, which includes about 133 species, is found exclusively in the Americas, and occupies a range of habitats including rainforests and deserts. Hemipepsis has 180 species and is found in tropical regions on every continent.
Although tarantula hawks get their fame and their name by hunting tarantulas, only larval wasps actually feed on arachnids. The adults actually consume nectar and fermented fruit, like other hymenoptrids like bees and hornets. In fact, many species of flowers rely exclusively on pollination by tarantula hawks. The painful sting they carry is enough to keep away potential predators. In general, however individuals are not aggressive and won't utilize their defenses unless provoked. In addition, though the sting is extremely painful to humans, it is not venomous and doesn't require medical attention unless it triggers an allergic reaction.
Members of both Pepsis and Hemipepsis are active during the daytime, and spend most of their time foraging. In the summer, females will also actively hunt for prey in which to lay their eggs, while males will practice a behaviour called 'hill-topping', in which they perch on a tall flower or shrub and wait for reproductive females to pass by. Males can become defensive of their territories, but lack stingers as they have no need to hunt.
When males locate a receptive female, they engage in elaborate aerial dances to entice her to mate with them, sometimes reaching heights of over 305 m (1000 ft). After a male and female mate, they go their seperate ways; males to find another partner, and females to find a source of prey. Once a female has located a suitable tarantula, she stings it-- the venom she injects paralyses the arachnid but keeps it alive. She then drags it back to a specially prepared burrow, where she lays her egg inside the spider and covers the burrow.
The egg hatches about 3-4 days after being laid, and begins consuming its host. The sex of the larva depends on fertilization; unfertilized eggs produce males, while fertilized eggs produce females. Over the next several weeks, the larva will consume the tarantula in its entirety, keeping it alive as long as possible and going through several molts. Eventually the larva forms a pupa, and 2-3 weeks later emerges as a fully mature adult. Both sexes have fairly short lifespans: males only live for a few weeks, and females only live for 4-5 months, but in that time they will produce over 13 eggs.
Tarantula hawks are among the largest wasps in the world. The very largest can grow up to 6.5 cm (2.5 in) long, and have wingspans to match. The females' stinger is equally impressive, reaching a length of up to 12 mm (0.47 in). Species can come in a variety of colors, most commonly orange, blue, or black, with bright orange or red wings. These features, combined with the tarantula hawks' long, hooked claws and large eyes, make members of any species easily distinguishable from other wasps.
Conservation status: No species of tarantula hawk wasps is currently threatened, although many species are facing habitat destruction and a decline in their primary prey. One species of tarantula hawk, Pepsis grossa, is the official insect of the state of New Mexico in the United States.
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Hemipepsis ustulata by Gary McDonald
Elegant tarantula hawk wasp (Pepsis menechma) by Will Stuart via iNaturalist
Hemipepsis tamisieri by Debbie Hall
