Central Sierra
University of California
Central Sierra

Forest Research and Outreach Blog

Replanting the Sierra Nevada after an ecological catastrophe

Reposted from UCANR News

Given California's changing climate, should Sierra Nevada residents replant pine trees after so many died during the 2010-2016 drought? The short answer is yes, says Susie Kocher, UC Cooperative Extension forestry advisor.

“We have every reason to believe that pines will continue to be an important part of mixed conifer forests in the Sierras,” Kocher said.

Dead trees can be seen in the foreground and on the distant mountain side. (Click on photos for higher resolution.)

Kocher spoke at a meeting for UC Master Gardeners, volunteers who provide landscape advice to the public in California. Questions have been coming in to Master Gardener hotlines from mountain residents wondering what to do after unprecedented tree loses in the last few years.

Most California forests are suffering from severe overcrowding due to 100 years of aggressive fire suppression and selective harvesting of the largest and most resilient trees. They were then subjected to five years of drought.

“There were just too many stems in the ground,” Kocher said. “The drought was very warm, so trees needed more water, but got less. These were optimal conditions for bark beetles.”

Western pine beetle is a native pest that attacks larger ponderosa pine and Coulter pine trees weakened by disease, fire, injury or water stress. Bark beetles are tree species specific, so other beetles target other species of trees in California's mixed conifer forests. Typically, bark beetles bore through tree bark and create long winding tunnels in the phloem. An aggregating pheromone attracts additional bark beetles to the tree, and heavily attacked trees invariably die.

Healthy pine trees can fight off bark beetle attack by secreting pitch. Trees weakened by drought are unable to fend off an attack. In this photo, a pine beetle is stuck in pitch that oozed from the tree.
Evidence of bark beetle attack are exit holes on the outside, left, and winding galleries under the bark.

During the drought, 102 million Sierra Nevada trees died from bark beetle attack or simply lack of water; 68 million of those died in 2016 alone. But after the abundant rainfall in the 2016-17 season, the bark beetle population seems to have crashed.

Landowners with 20 acres or more may be eligible for a state cost-sharing program to remove trees, reduce the fire hazard and replant new seedlings. Landowners in mountain communities who wish to revitalize their properties can contact local UC Master Gardeners for recovery advice.

UC Master Gardeners are plant enthusiasts who have passed an intense training program presented by UC academics. They participate in continuing education annually to update and maintain their knowledge. More than 60 Master Gardeners from Mariposa, Madera and Fresno counties gathered in Oakhurst in October to learn from UC scientists how to work with mountain homeowners whose towering trees have died. Similar training sessions, all funded by a grant from UC Agriculture and Natural Resources, were held in El Dorado and Tuolumne counties in June.

UCCE specialist Jodi Axelson points out bark beetle damage.

“There is life after beetles,” said Jodi Axelson, UC Cooperative Extension forestry specialist at UC Berkeley.

“Eco systems are stretched, and then they come back,” she said. “You must remember the time scale of forest change is long and pines have been a major species in the Sierra Nevada for at least 28,000 years. As long as there have been pines, there have been bark beetles.”

The scientists suggest that people who own forestland take a step back and assess the landscape after their dead trees have been removed.

“We're seeing a lot of young cedar and white fir surviving the drought. Oaks seems to be doing really well,” Kocher said.

She suggests landowners thin young trees so available sun and soil moisture are focused on the healthiest trees. Water seedlings that are receiving more sun than before to reduce stress. Planting native conifers is the best option. Due to climate change, she recommends choosing trees from a slightly lower elevation to hedge against warmer temperatures in the future.

Pines are adapted to the California forest, but may need help to regenerate. When the ground is moist in the late fall or spring, plant seedlings 10 to 14 feet apart. New trees should be planted well away from homes to maintain defensible space and at least 10 feet from power lines.

“Please don't set them up for future torture,” Kocher said. “That's just sad.”

UCCE forestry advisor Susie Kocher, center, speaks during a field trip to a forest where many trees were killed by bark beetles.

To help the new trees become established, cover the ground around the tree, but not touching the bark, with two or three inches of mulch and irrigate weekly during the dry season for the first few years.

Questions about special circumstances may be directed to local UC Master Gardeners. Find the local program here: http://mg.ucanr.edu/FindUs/

Pouch fungus is evidence of a bark beetle kill. The beetles carry fungus into the cambial layer of the tree on their bodies. On recently killed trees, small white conks, the fungus' fruiting body, issues from bark beetle tunnels.
UC Master Gardeners learn from experts about replanting conifer forests.




Posted on Wednesday, October 25, 2017 at 1:37 PM
  • Author: Jeannette Warnert

Lessons to be learned from Northern California fires

Reposted from the UCANR Green Blog


A wind-driven fire glows ominously over homes in Sonoma County in October 2017. Photo by Adam Giusti

It's Deja Vu all over again 
Yogi Berra

Once again I'm asked to provide some perspective on yet another catastrophic situation affecting the North Coast. In 2015, it was the Valley Fire. In 2016, it was the Clayton Fire. This year there are so many fires I'm having difficulty recalling their names...14 at last count.

The cause for these 2017 conflagrations will be apparent once the elements of the fires are assessed. Tornadic winds hitting 50 mph Sunday, October 8, will most likely have started most if not all. Winds of this intensity can ignite fires by impacting electrical infrastructure by breaking lines and causing transformers to explode. The cause of the fires will come out in time. Thick stands of vegetation, the result of mid-20th century land management practices, years of fire suppression, homes built in rural locations in steep terrain, old legacy roads too small to accommodate modern fire-fighting equipment, and exurban development without the necessary resources to address fire prevention. All this leads to almost impossible conditions to arrest a fire being pushed by wind.

I would argue there is no better fire-fighting force in the world than those found in California. What these men and women do is nothing short of extraordinary. But they are faced with an impossible task in the absence of an equally focused program of fire prevention.

Cobb Mountain after the Valley Fire burned more than 76,000 acres in 2015. UC Cooperative Extension helped replant the area with ponderosa pine seedlings.

What have I learned from Lake County as a result of the Valley and Clayton fires?

The Lake County fires have provided insights that can help with the recovery and reconstruction of the most recent events. Specifically, resources must be secured to assist landowners and communities in better incorporating fire resilience into local rural and suburban planning and projects, to prepare for the eventuality of another fire by creating and maintaining conditions that allow the fire to be controlled before getting out of hand. Admittedly, the recent fires were wind-driven events that became uncontrollable. However, these fires are the exception to the rule. There are hundreds of fires a year in California that are quickly controlled and extinguished. Fire resiliency must incorporate plans and projects that can address less catastrophic conditions, in the hopes of arresting a fire before it becomes a conflagration.


Fire-fighting equipment may need to be scaled to accommodate old, narrow rural roads to improve fire response.

Other aspects for communities to consider when addressing fire resiliency may include fire-fighting equipment scaled to accommodate old, rural roads, resources to retrofit old roads to accommodate evacuees and first responders, and rural lands with poor or non-existent internet service need to re-establish fire sirens to alert residents of impending danger. Local statutes need to establish and enforce vegetation management standards on absentee parcels. And, finally, a sustained dialogue addressing fire resiliency must be incorporated into all land-use planning discussions to help landowners recognize and implement actions to help reduce the risk of catastrophic fire.

None of this will be easy or inexpensive. But neither is fighting hundreds of thousand acres of wildland fires every year.

Admittedly, the weather conditions responsible for these fires may negate the best plans and efforts. But again, those conditions are the exception to the rule.

For every acre burned this year there are ten more, in the same condition, that didn't, providing next year's opportunity for a conflagration. The road forward to address California's wildland fire threat is long, and full of twists and turns. But as with all long journeys, each begins with the first step. 

Greg Giusti is a UC Cooperative Extension advisor emeritus specializing in forests and wildlands ecology.



Posted on Saturday, October 21, 2017 at 8:40 AM
  • Author: Greg Giusti

Houses likely burned from the inside out, says UCCE forest advisor

Reposted from UCANR News


Fire damage from the 1991 Oakland Hills fire. Buildings can burn quickly if embers get inside and fall on flammable materials.

Preventing embers from getting inside may save homes

Photos and video of the Northern California communities that have been hit by wildfires this week show buildings reduced to ash. How could so many homes and businesses burn so quickly in Wine Country fires? Many houses that burned to the ground in the Northern California fires likely burned from the inside out, says Yana Valachovic, UC Cooperative Extension forest advisor for Humboldt and Del Norte counties.

Red hot embers carried on the wind can enter the attic via the venting. “In the case of the wind-driven fires on October 8, these fires created ember storms that blasted little coals into everything in their pathway,” Valachovic said. These embers also create small spot fires near the home that fuel new sources of embers.

Weather played a large role in these fires and generated a fire storm of embers that ignited grass, shrubs, trees and anything in its path. “While the landscape can be the fuse, the homes really can be the most burnable part of the landscape,” Valachovic said. “These embers likely lodged in the small spaces and openings of homes and buildings. A common location is for the embers to enter via attic venting or HVAC systems distributing little fires into the buildings.

“Embers also landed on receptive leaves, outside furniture, and other flammable materials outside the buildings that created fires adjacent to the buildings. Once enough buildings were engulfed in fire, the radiant heat of each building fire led to exposures on the neighboring buildings, creating a house-to-house burn environment.”

Embers carried on the wind can ignite dry plant material like pine needles and create more embers that may enter homes through vents.

Residents can reduce the risk of embers setting their house on fire by removing dry plants around the structure.

“These fires remind us that everyone in California could help the fire situation by managing the vegetation, leaves in the gutters and decks, newspaper piles, brooms and other flammable sources near to their houses now before they get the evacuation call,” Valachovic said. “If you are likely to have to evacuate soon, temporarily covering or sealing up the vents with metal tape or plywood can help harden your home to an ember storm.”

Steve Quarles, UC Cooperative Extension advisor emeritus, who spent his career studying fire behavior on building materials and around homes, created an online Homeowner's Wildfire Mitigation Guide at http://ucanr.edu/sites/Wildfire. Quarles, who now does research for the Insurance Institute for Business and Home Safety, demonstrates how embers can ignite and quickly engulf a house in flames in a video https://www.youtube.com/watch?v=IvbNOPSYyss. After the 3-minute mark, video shows embers drifting up and flying through a screened vent into the house, where they could ignite combustible materials in the attic resulting in fire starting on the inside of the home.

“If you have time to prepare your home, use the wildfire last-minute check list at http://disastersafety.org/wp-content/uploads/2016/07/IBHS-Wildfire-Last-Minute-Checklist.pdf,” Valachovic said.

Valachovic has co-authored publications in home survival in wildfire prone areas http://anrcatalog.ucanr.edu/pdf/8393.pdf and how landscape plants near homes can create more vulnerability to wildfire http://anrcatalog.ucanr.edu/pdf/8228.pdf.

Once these fires are extinguished, a more detailed analysis will be possible.

“Past wildfire events have shown that this is the common way homes in the wildland urban interface (WUI) burn, and this scenario was likely translated to the urban environment,” she said.  

Posted on Tuesday, October 17, 2017 at 9:04 PM
  • Author: Pam Kan-Rice
Tags: embers (2), home loss (1), wildfire (35), Yana Valachovic (3)

Science Tuesday: Going Nuclear

Reposted from the Fire Adapted Communities Learning Network

On Labor Day weekend, my friends and I canceled a vacation rental on the Trinity River because of the heat and smoke. It was predicted to be 112 degrees inland that weekend, and we figured we'd be crazy to subject ourselves (and our posse of toddlers) to that when we could stay on the coast and enjoy fresh air and cool temperatures. Smart, right?

Screenshot of temperatures near Eureka during Labor Day weekend. Eureka was 102; further inland, temperatures ranged from 67 to 76.

Credit: Jason Barnes

Saturday morning, we made breakfast at my friend's house and watched the temperature climb. By 10 a.m., it was over 80 degrees, and by noon, it was nearing 100 — unbelievably hot for our foggy redwood coast. And on top of the heat, it was the smokiest I've ever seen it here. Turns out, we hadn't escaped the heat or the smoke.

But here's the weird thing: the inland areas, which were predicted to be unusually hot that weekend, were actually cooler than the coast. My husband, who was working on the Eclipse Complex in the Klamath Mountains — in the heart of the projected heat wave — experienced a high in the low 80s that weekend. Meanwhile, we were grappling with almost unprecedented heat here by the ocean. To have a double-digit difference in temperature between the inland areas and the coast is the norm here, but the coast is never the hotter of the two.

The odd temperature patterns that weekend reminded me of an old paper I read years ago — something about the cooling effects of forest fire smoke, and the potential to use wildfires to better understand the potential impacts of “nuclear winter.” An odd topic, but intriguing, too.

Interestingly, in looking back at the paper, I realized that it was based on data collected in the Klamath Mountains exactly thirty years before this year's hot, smoky Labor Day weekend. The author, Alan Robock, analyzed surface temperature data from weather stations across northern California and southern Oregon, and he found that smoke from nearby wildfires had significant cooling effects in the Klamath River canyon in September of 1987 — temperatures were more than 27 degrees below normal for an entire week and more than 9 degrees cooler than normal for most of the month. During that time, the combination of an inversion and wildfire smoke created a positive feedback loop: smoke trapped by the inversion cooled the surface air temperature, which strengthened the inversion and trapped even more smoke. Of course, the smoke did more than cool the air that month; Robock notes that it also caused severe respiratory problems for people who were living in that area, and even caused tomato plants to shrivel up and die.

Wildfire smoke inversion occurring on the horizon; temperature inversions trap smoke

Inversions are common in areas with complex topography, like the Klamath Mountains. Here's an inversion during a prescribed burn in the Klamath River canyon (Northern California Training Exchange, 2013). Credit: Lenya Quinn-Davidson

More recent studies show other important effects of temperature inversions. Earlier this year, Becky Estes and others published a paper in Ecosphere that looked at the factors influencing fire severity in the Klamath Mountains in 2006 — a year that had moderate burning conditions and is thus representative of years when wildfires might be managed for resource benefit. Of all the weather variables they looked at, temperature inversions had the strongest influence on fire severity that year. Earlier work by Miller et al. (2012) had noted similar patterns, including more surface fire and less crowning under inversions. 1987 and 2008, two of the biggest fire years in our region in the last several decades, had lower than average fire severities thanks to widespread temperature inversions.

Collectively, these studies reveal interesting tensions between humans and fire — not just here in the Klamath Mountains, but everywhere. In some ways, the inversions and smoke are producing conditions we want to see on the ground: lower fire intensities, cooler temperatures, etc. But these can come at the cost of unlivable air quality (not to mention stunted vegetables and wine that tastes like smoke!). And this isn't just about inversions — it's really about us finding ways to live in the crossfire of the natural checks and balances of these systems. We know that we need more fire, and that we need to take advantage of moderate burning conditions, even if that means more smoke. We just need to find good ways to do it — that's what fire adaptation is all about. (Also, I'd be lying if I said Robock's thoughts on nuclear winter didn't seem a little more relevant now than they did last time I read that paper … might be worth revisiting!)


Estes, B. L., Knapp, E. E., Skinner, C. N., Miller, J. D., & Preisler, H. K. (2017). Factors Influencing Fire Severity Under Moderate Burning Conditions in the Klamath Mountains, Northern California, USAEcosphere8(5).

Miller, J. D., Skinner, C. N., Safford, H. D., Knapp, E. E., & Ramirez, C. M. (2012). Trends and Causes of Severity, Size, and Number of Fires in Northwestern California, USA. Ecological Applications22(1), 184-203.

Robock, A. (1988). Enhancement of Surface Cooling Due to Forest Fire SmokeScience242, 911-913.

Posted on Friday, September 29, 2017 at 11:02 AM
  • Author: Lenya Quinn Davidson
Tags: cooling (1), inversions (1), prescribed fire (6), smoke (1), temperature (1)

The Bug Collection: A Brief Tour of the Essig Museum of Entomology

Reprinted from California Magazine, UC Berkeley Alumni Association


Pete Oboyski worries about bugs eating his bugs.

Scratch that. The collections manager at the Essig Museum of Entomology, Oboyski worries about insects eating his insects—specifically, a family of beetles known as dermestids, which, should they make their way in, could reduce the museum's 6-million-plus specimens to powdery ruin. As any self-respecting entomologist will tell you, true bugs are only a subset of the much larger taxonomic class of Insecta. Indeed, Oboyski's ilk tend to be a bit pedantic on that point. “Bugs” is a colloquialism they'd squash if they could.

The dermestidae, often called skin beetles, eat skin, just as the name suggests. They also eat hair, hide, fur, feathers, and meat—basically, everything but bone. And while museum curators dread the damage the ubiquitous arthropods and their larvae can do, they also make use of them.

Oboyski points at one wall of the bunker-like space that houses the Essig. On the other side of the wall is Berkeley's Museum of Vertebrate Zoology. “The vertebrate people keep a colony of dermestids just on the other side of that wall there, to clean carcasses. They like them because they do such a thorough job of it, removing every last speck of flesh.” He says it's the same colony they've had since the museum started in the early 1900s. “They use a variety that's a little too large to get into my cases, fortunately, which is the only reason I can sleep at night.”

The tightly constructed, glass-topped wooden cases in which insects are mounted on pins are the entomologist's stock in trade. The Essig holds thousands of them, all slotted in racks on track shelving that can be moved by hand cranks. It's a vast bug library filled with row after row of meticulously preserved specimens, all organized by order, family, genus, species, and subspecies. Everything in the collection is of the phylum Arthropoda—many in class Insecta,but no few Arachnida.

Something you generally won't find in the Essig is any living insects, although on this particular day Oboyski was making an exception, hatching some Australian walking sticks in a terrarium. Most of the time, live bugs are verboten, and Pete has lights and pheromone traps set up to catch any of the little buggers that might sneak in.

“If you had told me 50 years ago that we were going to sequence DNA from these specimens, I would have said, ‘What are you talking about?' Now we do it all the time. … So that's my attitude in terms of preserving these … because I have no idea what they're going to be used for in the future.”

One of the largest university collections in North America, the Essig's regional emphasis is primarily on California, but it also expands to the Pacific Rim, including the islands of the central Pacific. Oboyski, a moth specialist who earned his Berkeley Ph.D. in 2011, has identified nine new species himself—seven from Hawaii, and two from Tahiti. The museum's namesake, Professor E.O. Essig (1884–1964), author of the seminal text Insects of Western North America, was chiefly an aphid man. (Aphids, incidentally, are true bugs, part of the order Hermiptera, which, like all the other true bugs, have mouthparts adapted for sucking juices from plants … or, in the case of bed bugs, blood from people.) Essig was one of the leaders of the California Insect Survey, which grew the collection considerably in the 1930s.

“Museum” is a bit of a misnomer in this case. The Essig is strictly a research collection, made available to scientists for all manner of legitimate study, but only open to the general public a few times a year: on Cal Day, Darwin Day, and, this year, Homecoming. That said, education and outreach are a part of the Essig's charter. Schoolchildren often visit on tours, and when they do, Oboyski will show off what he calls the “Oh, my!” collection. These are the stars of the insect world: the glorious blue morpho butterflies, bizarre walking sticks, and the giant rhinoceros and Atlas beetles, which look like they could topple walls. Indeed, pound for pound, these macrobeetles are among the strongest animals in the world.

But the oohs and aahs and occasional shrieks elicited by these specimens are only a small part of the collection's value. More important is the research role they play, perhaps especially in terms of documenting ecological change over time. To the disinterested, the Essig may seem like a mausoleum, better digitized and discarded. (And in fact, digitization is underway, in part through volunteer and crowdsourcing efforts, with about 10 percent completed so far.) But to Oboyski, the physical collection itself is a vast storehouse of information that is constantly being mined in new ways.

Think about it, he says; we now have CT scans that allow us to scan the internal anatomy. We can look at stable isotopes to study their diets and how they've interacted with the environment. We can grind them up and extract DNA.

“If you had told me 50 years ago that we were going to sequence DNA from these specimens, I would have said, ‘What are you talking about?' Now we do it all the time. Fifty years from now, I have no idea what people are going to be doing. … So that's my attitude in terms of preserving these. I want to preserve them as pristinely as possible for as long as possible, because I have no idea what they're going to be used for in the future.”

In the meantime, for those who get heebie-jeebies just thinking about bugs, it's probably good to remember that insects are crucially important to us in myriad ways, both “good” and “bad.” Insects pollinate our crops and also sometimes destroy them. They control disease but also spread it. When ecosystems are in balance, insects check each other's populations. And even those destructive skin beetles perform a crucial service: They are natural recyclers, part of life's great dust-to-dust cycle.

To give a sense of how wondrous and important the insect world is to California, and to Berkeley researchers, we asked Pete Oboyski to introduce us to a dozen or so species from the Essig's vast collection, beginning with the cutest of all, the ladybugs—which, at the risk of being pedantic, we have to point out are not really bugs at all.


The Lady Bug

 The convergent ladybug, or more properly, convergent lady beetle (Hippodamia convergens),is a familiar sight in the Berkeley Hills, where large clusters of them often overwinter or carpet the forest floor. H. convergens is commercially gathered from large aggregations found in the Sierra Nevada for use as biological control—particularly of aphids, which are the beetle's primary food source. Oboyski says agriculture has changed the behavior of these beetles over time. Before water was diverted for agriculture, he explains, the aphid populations would naturally decline in the summer as vegetation dried up. In response, the lady beetles would move up into the hills. Now they tend to stay all season due to an abundance of food. “We've completely changed the dynamics of these beetles to a large part because of agriculture, which is supporting things they feed on.”


The Crane Fly

 The ubiquitous crane flies (Tipulidae) are doubtless among the most misunderstood insects found in our homes. Many of us mistake them for giant mosquitoes; others believe the flies prey on the mosquitoes, calling the flies “mosquito hawks” and “mosquito eaters.” In reality, says Oboyski, “they don't feed at all as adults. And they don't live long. But they're food for an amazing number of vertebrate animals—bats and birds and lizards and anything else that can catch one will eat it. So while [the crane flies] come out in abundance, like all those baby sea turtles heading for the ocean, only a couple of them actually survive to reproduce.” 


The Glassy-Winged Sharpshooter

 The glassy-winged sharpshooter (Homalodisca vitripennis) is a large leafhopper native to the American southeast. It is of special concern in California because the species carries a plant pathogen in its system that triggers a grapevine blight called Pierce's disease. The invasive H. vitripennis also made its way to Tahiti where, lacking any predators, the population exploded, leading to something called “the rain effect.” Oboyski explains, “They're sapsuckers, so they're drinking lots and lots of sugar water to get little bits of nitrogen, which they really need to build proteins. But most of that sap is just water, and so they need to pee.” In Tahiti, the sugar-water excrement coming from the trees was often so thick that it was like a rain shower. Luckily, researchers from UC Riverside were able to introduce a parasitic wasp to rein in what locals had taken to calling the “pissing fly.”


The Bedbug

 Probably no household pest is quite as repugnant to us as the bedbug (Cimicidae), which feeds on our blood at night. Not so long ago, Oboyski notes, bedbugs were just a fact of everyday life. “It wasn't until World War II and the chemical revolution and DDT that we were on the verge of chemically controlling them, and they disappeared for a few decades.” Now, however, they're resistant to DDT and other chemicals and are making their resurgence, much to the alarm of hotels and their guests. “I get calls from people who want to sue a hotel because they found bedbugs in their room. And the bedbugs are completely harmless. They aren't carrying any disease; there's just this connotation of being unhygienic. Whereas mosquitoes actually do carry diseases—but would anyone sue a hotel because they got bit by a mosquito? Probably not.”


The Tarantula Hawk

 When it comes time for the female tarantula hawk, the giant in the family of so-called spider wasps (Pompilidae), to lay its egg, it engages in an epic struggle with a tarantula. They're pretty evenly matched, observes Oboyski, and the stakes couldn't be higher. “If the wasp loses, it gets eaten; but if it wins, it paralyzes the spider with its sting, drags it off and buries it, and then lays its egg in [the spider].” As the larva develops, it feeds on the tarantula, carefully avoiding the host's vital organs so as not to kill it off. Although tarantula hawks are considered fairly docile, their sting is said to be extraordinarily painful. Arizona-based entomologist Justin Schmidt, best known for his “sting pain index,” calls the sensation “instantaneous, electrifying, excruciating, and totally debilitating.” Schmidt's advice: Lie down and scream.


The Gall Wasp

  On the other end of the size spectrum, the diminutive gall wasp (Cynipidae) grows its larvae in a plant growth called a gall. “Each gall is very specific to the wasp that laid it,” explains Oboyski. “It's the plant that grows the tissue, but somehow the wasp is telling the plant to grow this exact shape for [the wasp's] larvae. Along with the egg, they're introducing some enzymes that are turning on genes inside the plant.” But the story doesn't end there. “As if that's not enough, there are other wasps that want to lay their eggs there, too. So now you have interlopers. And then there are things like parasitic wasps that know there's some nice squishy larvae in there, and they insert a tube into the gall and lay their eggs inside those larvae. Then there are hyperparasitoids that lay their eggs inside the larvae that are inside the other larvae. And then there are things that feed on the galls outside. So a whole community arises from this tiny little wasp that caused the plant to swell up.”


The Carpenter Bee

Like termites, carpenter bees also burrow into wood. The valley carpenter bees (Xylocopa varipuncta) are named for California's Central Valley and are the state's largest native bees. Unlike honeybees, which were brought to the Americas from Europe, carpenter bees don't generally sting. Like honeybees, they're good pollinators. Due to the much-publicized colony collapse disorder, in which vast numbers of worker bees simply vanish from a honeybee colony, Oboyski says there has been a spike of interest in native pollinators. “We're not sure what's going to happen with honeybees, so the thinking is we'd better hedge our bets and see how we can get our native bees to provide the same services.”


The Africanized Bee

 Another bee that has had a lot of media attention is the Africanized bee, or “killer bee,” although less so lately. Oboyski says the Africanized bees are now hybridizing with our European honeybees, with mostly positive results, allaying earlier hysteria about wild swarms of killer bees attacking school children. “This fear that we're now going to have this more aggressive bee here is probably true, but the Africanized genes are mellowed out by the European genes.” What's more, he says, “the Africanized bees also bring resistance to some pests, like the mites that feed on the European bees. So it's actually improving their health.”

As for colony collapse disorder, Oboyski says it's still a bit of a mystery. “The leading suspects now are these neonicotinoid pesticides that [the bees] seem to be very sensitive to. But in my opinion, it's not likely to be a single factor at play. It's a species we've been managing intensely for a very long time. … They're boxed up one night in an almond orchard in California, and they wake up the next day in an apple orchard in Michigan, and it's very stressful. Neonicotinoids may just be the last straw.

“But there's been some really entertaining ideas of what happened to the bees. I remember someone saying they'd been taken up by the Rapture. They were pointing to the fact [the bees] disappear. It's not like you see a bunch of dead bees around. To me, that's not surprising because, you know, they're food. If there's a dead bee somewhere, something's going to eat it.”


The Bark Beetle

 California pine forests are being laid to waste as tens of millions of trees succumb to an epidemic of bark beetles, including mountain pine beetles and other relatives of the Scolytidaefamily of weevils. It may sound like an alien invasion, but it's not. Says Oboyski, “The bark beetles that are causing the problems are actually native here, and it's not that they've changed over the years. It's the way we've managed landscapes that has changed,” particularly in terms of clearcutting and fire suppression. Those practices, he says, have resulted in large monocultural stands and old decadent trees that are more susceptible to pest invasion than a “young, vigorous forest that's constantly refreshed by fires.” And, of course, drought has been an aggravating factor. “These beetles only attack stressed trees. If the tree is healthy, they get ‘pitched' out by the tarry sap they produce. But in a stressed tree that's attacked by lots of beetles at the same time, there's not enough pressure behind that pitch to push the beetles out.”


The Termite

 Bark beetles only infest live trees, whereas termites (Termitoidae) come in long after the tree is dead. And unlike the bark beetles, which aren't feeding on the tree but rather using it to make their nests, termites are actually eating it. To accomplish that, however, they need help. “Termites can't actually digest wood themselves, but they have this gut fauna inside that can actually convert the lignin of the plant into digestible food.” The symbionts reside in the parts of the termites' gut that get shed when they molt, adds Oboyski. “That means every time that they molt, they lose their ability to digest wood. So they have to do a fecal transfer to get them back again. So they will feed on the feces of other termites to get those bacteria back.”


The Xerces Blue

The Xerces blue (Glaucopsyche xerces), like the California Golden Bear, no longer exists. Endemic to the erstwhile dunes of San Francisco's Sunset District, the powder-blue gossamer-winged butterfly was presumably done in by urban development. Showing the Xerces at the Essig, Oboyski says, “It's rare to be able to document extinctions in the insect world, but this is one we're fairly certain about.” He calls this butterfly the “poster child of invertebrate extinction.” The Xerces blues were part of a family of little blue butterflies, some of which “have ridiculous relationships with ants. The ants actually take them into their colonies and feed them and take care of them.” It seems the caterpillars release pheromones that smell like the ants. The last known Xerces blue was netted by Berkeley alumnus and later UC Davis entomologist W. Harry Lange '33, in the Presidio on March 23, 1941. “I always thought there would be more,” he lamented later. “I was wrong.”

Posted on Thursday, September 28, 2017 at 11:12 AM
  • Author: Pat Joseph

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