Home & Garden Columns
This is not an owl column per se, but it was inspired by a recent conversation with an owl person: Maggie Rufo of the Hungry Owl Project, who brought a barn owl named Wookie to a Keep Barn Owls in Berkeley event. We were talking about barn owl diets, and Rufo mentioned finding a lot of Jerusalem cricket remains in the nests she monitors.
“I didn’t know what they were at first,” she said. “They looked like extraterrestrials.”
That’s not an uncommon reaction to encountering a Jerusalem cricket, alive and intact or not. Both the California Academy of Sciences and the Los Angeles County Natural History Museum say they get more inquiries about these insects than about any other invertebrate species, mostly along the lines of “What in God’s name is this?” and “Will it bite?”
The accompanying photograph conveys the unsettling appearance of these good-sized grasshopper relatives. To me they are uncannily like the plastic cootie bugs of the ‘50s (not the more recent cootie incarnation). The Navajo call them wo see ts inii, which I have seen variously translated as “old bald-headed man” or “bone-neck beetle,” and some Spanish-speakers call them niñas de la tierra, “children of the earth.” They’re also known, without foundation, as “potato bugs.”
Their nearest relatives appear to be the extraordinary wetas of New Zealand, the namesake for that special-effects outfit that was involved in the Lord of the Rings movies. Wetas, up to 6 inches long with a record weight of 2.5 ounces, fill the ecological niche of the small mammals that never reached the islands.
As it happens, Jerusalem crickets don’t bite, and although they chew on roots, they are not particularly important garden or agricultural pests. Their social behavior has interesting complexities, and David Weissman at the Academy has found that they’re a paragon of California’s biodiversity.
(I have never seen a satisfactory explanation of the name, by the way. They don’t come from Jerusalem: they’re North American natives. And they’re not the same as the Mormon crickets that devoured the Utah settlers’ crops, which are altogether more conventional grasshopper types).
Jerusalem crickets don’t swarm like locusts or Mormon crickets; they lead solitary subterranean lives. It takes some doing for males and females to get together. Other grasshoppers and crickets use modified wing and leg structures to produce courtship calls. But those kinds of stridulations wouldn’t carry far through soil. Instead, a Jerusalem cricket of either sex signals potential mates by slamming its abdomen against the bottom of its burrow.
It used to be assumed that there were only seven species of Jerusalem cricket in California. However, in analyzing their drumrolls, Weissman has detected at least 50 distinct patterns. Although these different drummers may appear identical, he suspects each pattern may represent a separate species; the new ones are still in the process of being scientifically described. Like birdsong, the drumming provides a way for females to locate males of the appropriate species (and apparently vice versa).
Why so many species is a matter of conjecture. Some groups of plants and animals seem prone to bursts of speciation: California also has high diversity in manzanitas, chipmunks, and slender salamanders. Among animals, populations of creatures with small home ranges and limited mobility—and Jerusalem crickets fit that profile—may become isolated from each other and follow divergent genetic and adaptive pathways. Drumrolls, songs, or other forms of courtship communication then act as reinforcers of the new species boundaries, preventing the sharing of genes among formerly close relatives.
When Jerusalem crickets pair off, the ensuing courtship is highly strenuous. And as in their distant mantid relatives, it often ends with the female dining on the male—a last gift of protein to nourish the eggs that he’s hopefully fertilized.
Even individuals who escape this Liebestod are likely to end up being eaten by something else. When they emerge from underground, the insects are conspicuous, slow, and defenseless. It’s not just the barn owls: gray foxes are particularly fond of Jerusalem crickets, and low-flying pallid bats, skunks, lizards, snakes, and toads also take their toll.
If they turn up in your yard, don’t panic. They’re not only an important link in the food chain: they may actually be doing you a favor by eating detritus and aerating the soil.