Posts Tagged: hover fly
Hide the cactus! There's a Mexican cactus fly in our midst.
A large black fly hovers over a Mexican sunflower (Tithonia) in our bee garden and then drops down to sip some nectar. At first glance it looks like a carpenter bee but this one hovers like a syrphid fly, aka flower fly or hover fly.
"Hover fly," I say.
Entomologists Martin Hauser, Lynn Kimsey and Robbin Thorp quickly identified the critter.
Hauser, senior insect biosystematist with the Plant Pest Diagnostics Branch of the California Department of Food and Agriculture, says it's in the genus Copestylum (with over 350 species in the new world) and figured it to be the species, mexicanum, commonly known as the Mexican cactus fly.
Said Lynn Kimsey, director of the Bohart Museum of Entomology and professor of entomology at UC Davis: "Nice, this is actually a kind of syrphid flower fly, better known as a cactus fly. The larvae breed in rotting cactus tissue."
Native pollinator specialist Robbin Thorp, emeritus professor of entomology, also figured it to be a Mexican cactus fly, Copestylum mexicanum. "It's commonly known as a cactus fly (Syrphidae, Tribe Volucellini). "It used to be in the genus Volucella, But now it's in the genus Copestylum."
This fly is not small. It's about 3/4 of an inch long. It lays its eggs in rotting plant material "and they really like rotting cacti," Hauser commented. "As far as I know, they only go into dying cacti and do not attack healthy cacti…. But there is actually not much known about their biology."
The resident cacti expert at our house is worried, showing his best prickly pear expression. He quickly canvasses the yard. Whew! No rotting cacti. All thriving and in good health.
So far, so good...
Black hover fly, aka Mexican cactus fly, sipping nectar from a Mexican sunflower (Tithonia). (Photo by Kathy Keatley Garvey)
Side view of the black syrphid fly, a Mexican cactus flower. (Photo by Kathy Keatley Garvey)
Mexican cactus fly ready to take off. (Photo by Kathy Keatley Garvey)
The 40 mile-per-hour howling wind didn't seem to bother the syrphid fly, aka hover fly and flower fly.
It clung to a blossom on the tower of jewels, Echium wildpretii, and proceeded to nectar. Its wings sparkled in the morning sun.
This is a pollinator and one that's often mistaken for a honey bee.
A honey bee it isn't. It's a fly.
If you want to read more about them, be sure to check out entomologist Robert Bugg's UC ANR publication, Flower Flies (Syrphidae) and Other Biological Control Agents for Aphids. Click on the link for access to a free 25-page PDF.
Syrphid fly nectaring on tower of jewels, Echium wildpretii. (Photo by Kathy Keatley Garvey)
Syrphid sparkles in the early morning sun. (Photo by Kathy Keatley Garvey)
Ah, the little intricacies of life...
We were walking along a stretch of the coastal town of Bodega Bay when we spotted something we'd never seen before: a bubble on a syrphid fly.
Syrphid flies, also known as hover flies or flower flies, are pollinators, just like honey bees. As floral visitors, syrphids are often mistaken for bees. They're not. They're flies.
But what was the bubble?
Several of our UC Davis entomologists weighed in.
"Weird, I wonder if that's an egg," said one entomologist. "Looks like the ovipositor is extended."
Said another: "If this were a honey bee, I would suggest that you shot your first defecation photo." (Spoken like the true honey bee expert he is!)
And another: "My guess is that droplet is fly (note: brace yourself--here comes the "p" word) poop, composed mostly of digested pollen grains that the flies commonly feed on. If you look closely at the abdomen of these flies, you often see the gut outlined with yellow or orange through the semi-translucent membrane areas of the abdomen due to the pollen they have ingested."
We asked fly expert and senior insect biosystematist Martin Hauser of the California Department of Food and Agriculture's Plant Pest Diagnostic Branch for an I.D. of this syrphid fly. "A female Sphaerophoria," he said.
And, oh, yes, the bubble is not an egg. It's the "p double oh p" word with pollen inside. Hauser pointed out that the eggs are oval and white, so the yellow bubble is not an egg. Check out this photo of syrphid eggs on the bugguide.net website, Hauser said. And here's a image on bugguidenet.com of the syrphid fly ovipositing.
Sounds like a good question for an Entomology 101 quiz...
Or the Linnaean Games...
Syrphid fly (female Sphaerophoria), as identified by senior insect biosystematist Martin Hauser of the CDFA. (Photo by Kathy Keatley Gavrey)
Close-up of "The Girl and the Bubble." See text above for what the bubble is. (Photo by Kathy Keatley Garvey)
“If you were an aphid on a head of lettuce, a hoverfly larva would be a nightmare. They are voracious eaters of aphids. One larva per plant will control the aphids.”
That's what organic researcher Eric Brennan of the Agricultural Research Service (ARS), U.S. Department of Agriculture, told reporter Jim Robbins in a recently published New York Times article.
Headlined "Farmers Find Organic Arsenal to Wage Wars on Pests," the news story drew attention to why natural enemies are "key to the organic approach."
Brennan is based in Salinas Valley, known as "The Salad Bowl of America." It's reportedly where 80 percent of Americans get their greens.
And it's where the lettuce aphid gets its lettuce.
To help resolve the problem, organic farmers are planting alyssum in their lettuce beds. Hover flies "live in the alyssum and need a source of aphids to feed their young, so they lay their eggs in the lettuce," Robbins wrote. "When they hatch, the larvae start preying on the aphids."
Could be that the "salad days" are over for the aphids--thanks to Brennan, alyssum and hover flies.
Aren't syrphid flies grand?
Syrphid flies, aka hover flies or flower flies (family Syrphidae), are especially grand in a Calandrinia grandiflora, aka rock purslane.
Often mistaken for honey bees, these insects hover over flowers, wings spinning like helicopters, and then dart inside a blossom to feed on pollen and nectar.
We spotted a brightly colored syrphid on a rock purslane in our garden last Sunday. It appeared in no hurry to leave its host.
Is it true that this colorful fly is in the same order (Diptera) as the common housefly? It is.
Hover flies are found everywhere in the world except Antarctica. For a look at some of the species, check out BugGuide.Net. The site contributors are self-described naturalists "who enjoy learning about and sharing our observations of insects, spiders, and other related creatures."
Another great source is entomologist Robert Bugg's 25-page booklet, "Flower Flies (Syrphidae) and Other Biological Control Agents for Aphids in Vegetable Crops," published in May 2008 by the University of California, Division of Agriculture and Natural Resources (UC ANR). You can download it for free by accessing this page.