3/26/2020 Entomology Today
If you cleared fallen leaves from your lawn last fall, did you deposit them along the edge of your lawn, where grass meets woods? If you did, you might have unwittingly created an ideal habitat for blacklegged ticks.
In areas of the United States where ticks that carry Lyme disease-causing bacteria are prevalent, residential properties often intermingle with forested areas, and ticks thrive in the “edge habitats” where lawn and woods meet. While many homeowners heed the advice to clear their lawns of fallen leaves in autumn to avoid creating tick-friendly habitat in high-use areas, a new study on tick abundance in leaf litter says raking or blowing leaves just out to the forest edge is not enough.
“Our study showed that the common fall practice of blowing or raking leaves removed from lawns and landscaping to the immediate lawn/woodland edges can result in a three-fold increase in blacklegged tick numbers in these areas the following spring,” says Robert Jordan, Ph.D., research scientist at the Monmouth County (New Jersey) Mosquito Control Division and co-author of the study published today in the Journal of Medical Entomology
Instead, Jordan and co-author Terry Schulze, Ph.D., an independent medical entomologist, suggest homeowners either take advantage of municipal curbside leaf pickup (if available), compost their leaves, or remove leaves to a location further into the woods or further away from high-use areas on their property. “The thing homeowners need to keep in mind is that accumulations of leaves and other plant debris provide ideal host-seeking and survival conditions for immature blacklegged ticks,” says Jordan.
In their new study, Jordan and Schulze set up test plots on three residential properties in Monmouth County, New Jersey, in the fall of 2017 and 2018. Each property had plots at both the forest edge and deeper within the wooded area. Some edge plots were allowed to accumulate leaves naturally, while others received additional leaves via periodic raking or leaf blowing. These “managed” edge plots resulted in leaf-litter depths two to three times that of the natural edge and forest plots.
The researchers then compared the presence of nymphal (juvenile) blacklegged ticks (Ixodes scapularis) and lone star ticks (Amblyomma americanum) in the test plots the following spring. In both years, the results for lone star tick nymphs were inconsistent, but the number of blacklegged tick nymphs in the managed edge plots was approximately three times that of the natural edge and forest plots.
“While we expected to see more ticks along lawn edges with deeper leaf-litter accumulation, we were surprised about the magnitude of the increase in ticks that resulted from leaf blowing or raking,” Jordan says. Fallen leaves provide blacklegged ticks with suitable habitat via higher humidity and lower temperatures within the leaf litter, as well as protection from exposure over winter. Previous research, meanwhile, has shown that people more commonly encounter ticks on their own properties than in parks or natural areas. And that, Jordan says, is a major reason why he and Schulze have been evaluating a variety of residential tick-prevention strategies in recent years. Landscape management is an important—and affordable—strategy to keep ticks at bay, he says. “On properties with considerable leaf fall, the best option would be complete removal of leaves from areas most frequently used–such as lawns, outdoor seating areas, and in and around play sets,” Jordan says. “If this is not possible or practical, leaf piles should be placed in areas least frequently used.
Where neither of these options is possible, or where leaf fall is minimal, mulching in place may be a good option, since this encourages rapid decomposition of leaves, which may reduce habitat suitability for ticks.”
By Jeremy Cox on March 18, 2020, Bay Journal
In Virginia, climate change is about as welcome as ants at a picnic. But across a portion of the state’s southeast, ants are part of the problem.
Since 1960, the annual average temperature in Virginia Beach, the region’s most populated city, has risen about 3 degrees, according to the National Oceanic and Atmospheric Administration. That warming trend has opened the door for fire ants — normally living in more southerly areas — to gain a stubborn foothold in the state, Virginia agricultural officials say.
And it’s growing larger.
“It’s an unfortunate side effect” of climate change, said Eric Day, a Virginia Tech extension entomologist. “We have warmer winters and warmer summers, so it certainly makes for good conditions for fire ants.”
The Virginia Department of Agriculture and Consumer Services announced in December that it was expanding its fire ant quarantine to five new counties and two separate cities. With the addition, the quarantine now spans one or two counties deep along the North Carolina border from just west of Interstate 95 east to the Atlantic Ocean, an area nearly the size of Connecticut.
The quarantine applies to both the black and red fire ant varieties, but the red is more commonly seen in Virginia, officials say. Both damage crops and deliver a nasty sting.
Since their accidental transmittal from South America to the United States in the 1930s, red fire ants have spread across most of the Southeast from the marshy tip of Florida to the windswept plains of Oklahoma.
When the first fire ant infestation was discovered in Virginia in 1989, agricultural officials blamed the interstate trade of plants and sod. They grew so widespread that by 2009 the state announced its first quarantine in the Hampton Roads region.
It has become clear with their continued spread westward along the state’s southern border in recent years that colonies are now marching up from the South on their own, Day said. That shift points for the first time away from humans as a cause for their proliferation in the state and toward a new climate reality, he added.
Fire ants resemble garden-variety ants, making them difficult to spot, experts say. Tell-tale signs of their presence are their mounds, which can reach up to 2 feet high and damage farm equipment. The ants themselves prey on corn, soybeans and other crops, causing further headaches for farmers.
Their sting, though, may be their defining attribute. Anyone who unwittingly wanders into a nest typically emerges with a foot or leg stippled with burning welts that turn into itchy, white pimples that last for days. In extremely rare cases, the victim can suffer deadly anaphylactic shock.
Christopher Brown, who works in purchasing and product development for the Lancaster Farms plant nursery in Suffolk, knows the sensation all too well. “It’s not like getting stung by a bee where it’s one sting and that’s it,” he said. “When you get bitten by a fire ant, you’re going to get bit five to 10 times depending on how long it takes you to realize you stepped on a fire ant mound.”
Suffolk was one of the first areas to be quarantined in 2009. The designation prohibits transporting anything that can carry fire ants out of the area unless it is certified as ant-free. Regulated items include gardening soil, plants, sod, used farm equipment and freshly cut timber.
At Lancaster Farms, workers blend an insecticide called Talstar into their pine bark potting material to kill any ants that may be there, Brown said. It takes a few cents’ worth of the chemical to treat each pot, he estimated; a 15-gallon pot includes about 10-cents’ worth. That expense adds up quickly because the nursery churns out hundreds of thousands of plants each year. “It’s a cost of business,” Brown said.
Fire ants are at the vanguard of an army of pests expected to trudge northward as fossil fuel emissions continue heat up the planet during this century. A U.S. Department of Agriculture-sponsored study in 2005 predicted that warming temperatures will increase the “habitable area” for red fire ants by 21% by the end of this century, pushing their upper boundary about 80 miles northward. By some time between 2080–89, fire ants could occupy a swath of Virginia as far west as Roanoke and stretching along a line bearing northeast toward the District of Columbia, according to the study. Maryland and Delaware can expect to see their first invasions by that time as well, it says.
Fire ants in VA
By Elizabeth Preston © 2020 The New York Times
Are humans the only animals that caucus? As the early 2020 presidential election season suggests, there are probably more natural and efficient ways to make a group choice. But we're certainly not the only animals on Earth that vote. We're not even the only primates that primary.
Any animal living in a group needs to make decisions as a group, too. Even when they don't agree with their companions, animals rely on one another for protection or help finding food. So they have to find ways to reach consensus about what the group should do next, or where it should live. While they may not conduct continent-spanning electoral contests like Super Tuesday, species ranging from primates all the way to insects have methods for finding agreement that are surprisingly democratic.
As meerkats start each day, they emerge from their burrows into the sunlight, then begin searching for food. Each meerkat forages for itself, digging in the dirt for bugs and other morsels, but they travel in loose groups, each animal up to about 30 feet from its neighbors, says Marta Manser, an animal-behavior scientist at the University of Zurich in Switzerland. Nonetheless, the meerkats move as one unit, drifting across the desert while they search and munch.
The meerkats call to one another as they travel. One of their sounds is a gentle mew that researchers refer to as a "move call:' It seems to mean, "I'm about ready to move on from this dirt patch. Who's with me?"
In a 2010 study, Manser and her colleagues studied move calls in a dozen meerkat groups living in the Kalahari Desert in South Africa. Groups ranged from six to 19 individuals. But the scientists found that only about three group members had to mew before the whole party decided to move along. The group didn't change direction, but it would double its speed to reach better foraging grounds.
Biologists call this phenomenon - when animals change their behavior in response to a critical mass of their peers doing something - a quorum response. Manser thinks quorum responses show up in human decision-making, too.
"If you're in a group and somebody says, 'Let's go for a pizza; and nobody joins in, nothing's going to happen;' she said. But if the pizza craver is joined by a couple of friends, their argument becomes much more convincing.
In the spring, you may discover a swarm of bees dangling from a tree branch like a dangerous bunch of grapes. These insects are in the middle of a tough real estate decision. When a honeybee colony splits in two, a queen and several thousand workers fly away from a hive together. The swarm finds someplace to pause for hours or days while a few hundred scouts fan out to search for a new home. When a scout finds a promising hole or hollow, she inspects it thoroughly. Then she flies back to the swarm, still buzzing on its tree branch. Walking on the swarm's surface, she does a waggling, repetitive dance that tells the other bees about the site she found - its quality, direction and how far away it is.
More scouts return to the swarm and do their own dances. Gradually, some of the scouts become persuaded by others, and switch their choreography to match. Once every scout agrees, the swarm flies off to its new home.
In his 2010 book "Honeybee Democracy;' Thomas D. Seeley, a Cornell University biologist, writes that we can learn a lesson from the bees: "Even in a group composed of friendly individuals with common interests, conflict can be a useful element in a decision-making process:'
African wild dog
Like pet dogs, African wild dogs spend some of their time enthusiastically socializing and some of it lazing around. Members of a pack jump up and greet one another in high-energy rituals called rallies. After a rally, the dogs may move off together to start a hunt - or they may go back to resting. In a 2017 study, researchers discovered that the decision to hunt or stay seems to be democratic. To cast a vote for hunting, the dogs sneeze.
The more sneezes there were during a rally, the more likely the dogs were to begin hunting afterward. If a dominant dog had gotten the rally started, the pack was easier to persuade - just three sneezes might do the trick. But if a subordinate dog started the rally, it took a minimum of 10 sneezes to prompt a hunt.
The researchers note that dogs might actually cast their votes via some other hidden signal. The sneezes could help the animals clear out their noses and get ready to sniff for prey. Either way, the wild dogs end their achoo-ing with a decision they all agree on.
Primates, our closest relatives, have provided lots of material for researchers studying how groups make decisions. Scientists have seen gibbons following female leaders, mountain gorillas grunting when they're ready to move and capuchins trilling to one another.
Sometimes the process is more subtle. A group may move across the landscape as a unit without any obvious signals from individuals about where they'd like to go next. To figure out how wild olive baboons manage this, the authors of a 2015 paper put GPS collars on 25 members of one troop in Kenya. They monitored the monkeys' every step for two weeks. Then they studied the movements of each individual baboon in numerous combinations to see who was pulling the group in new directions. The data showed that any baboon might start moving away from the others as if to draw them on a new course - male or female, dominant or subordinate. When multiple baboons moved in the same direction, others were even more likely to come along.
When there was disagreement, with trailblazing baboons moving in totally different directions, others would eventually follow the majority. But if two would-be leaders were tugging in directions less than 90 degrees apart, followers would compromise on a middle path. No matter what, the whole group ended up together.
Ariana Strandburg-Peshkin, an animal-behavior researcher at the University of Konstanz in Germany who led the baboon study, points out that unlike in human groups, among baboons no one authority tallies up votes and announces the result. The outcome emerges naturally. But the same kind of subtle consensus-building can be part of our voting process, too. "For instance, we might influence one another's decisions on who to vote for in the lead-up to an election, before any ballots are cast;' she said.
Below are two articles, one from the Washington Post (submitted by Charlene Uhl) and one from the Audubon Society (submitted by Bonnie Beers) that talk about how we can assist insect populations and feed birds properly. Must reads for backyard naturalists!
Welcome bugs into your yard
When It's Okay (or Not) to Feed Birds
Science Magazine and the Guardian
Climate change could increase bumble bees’ extinction risk as temperatures and precipitation begin to exceed
species’ historically observed tolerances. A new study adds to a growing body of evidence for alarming, widespread losses of biodiversity and for rates of global change that now exceed the critical limits of ecosystem resilience.
Read more about this topic here and here, or read the research study here.
Twenty-Year Study Shows How Climate and Habitat Change Impact One Mantid Species
By Paige Embry, Entomology Today
Ask someone what they know about praying mantids and chances are they’ll bring up the female biting the male’s
head off during mating. It happens, albeit only about 17 percent of the time, but those deaths can be a surprisingly
useful tool when studying mantid population changes over time. It’s one of the pieces of information tracked by
Lawrence Hurd, Ph.D., a professor of biology at Washington and Lee University, during a 20-year study
(1999-2018) of Tenodera aridifolia sinensis, the Chinese praying mantid.
The results were published in January in Annals of the Entomological Society of America.
In the last few years, studies finding widespread declines in insect abundance have made headlines. Hurd’s
long-term study uses one insect in one northern Virginia field to show how such declines can happen. Although the study only followed one species, Hurd and coauthorsnote that the findings should apply to other insects and spiders with a similar life cycle.
For this study, Hurd made good use of his resources. He had an insect of unusual size (7-10 centimeters) that beginners (his college ecology lab students) could easily recognize and catch. He also had a nearby field beginning its natural succession, which functioned as a laboratory because the mantids couldn’t easily escape from it. No other suitable fields were close by, and the mantids aren’t very mobile.
Five times between 1999 and 2018, on approximately the same day in September, Hurd sent his students across the
field in a “skirmish line” to collect, mark, and note every possible T. a. sinensis. Hurd writes in an email, “I always
try to base it [the class] on gathering good, usable data instead of just make-work data collection on a question that
has already been answered.”
To assess the reproductive success of the mantids, they went back after the first frost to collect the oothecae (eggs
laid in a gooey substance that hardens into a protective case). They brought the oothecae back to the lab, weighed them, and then returned them to the field. For the oothecae found on the stems of herbaceous plants, that meant “tying [them] on with sewing thread run through the dried foam surrounding the eggs.” Mantids do well in flowery fields with lots of arthropod prey. When succession trends in an area lead to more trees, the population of mantids should shrink. Over the 20 years of this study, two-thirds of the open field area was replaced by trees, and the number of mantids decreased dramatically.
However, succession was not the only factor impacting the mantids—climate change was as well. When a Chinese praying mantid lays her eggs, the sex ratio is even. By the time the mantids reach adulthood, males outnumber females. Once mating begins, the percentage of males starts to fall, prey to the females as well as any other
predators in the field. Eventually, the females become more common. Even though Hurd and the students sampled on essentially the same calendar day (September 12, 13, or 14) each year, they found that the proportion of males to the total population declined from more than 60 percent in 1999 to about 25 percent in 2018, showing that the mantids were further along in their life cycle.
It’s no surprise. For the last 40 years the growing season in northern Virginia has gotten longer and the summers hotter, so the mantids both hatch and reach maturity earlier. This means that some eggs may hatch before frost can put them into diapause, leading to death of the young nymphs and potentially adding to the population losses caused by the successional change.
In 2018, Hurd and his students found only three oothecae. In the fall of 2019, he saw no mantids, and found no oothecae after the first frost.
This study demonstrates the potential double whammy of habitat loss—even a naturally occurring one—and climate change. Hurd writes, “People are becoming worried about having to include insects in the mass extinction episode that many (including me) feel is already underway.” He says when he talks about this, people often respond with, “‘We gotta worry about bugs, too?'”
Unfortunately, as this study illustrates, the answer to that question is “yes.”
Find this article in Entomology Today here.
Find other articles on declines in insects and biodiversity on the Reading Corner page.
World’s fireflies threatened by habitat loss and light pollution, experts warn
Lightning bugs cannot signal to one another to mate if there’s too much light at night.
By Ben Guarino
Feb. 3, 2020 at 12:22 p.m. EST
(shared by Charlene Uhl, Class X)
Nearly 2,000 species of fireflies flit, crawl and sparkle across the planet. Some of these lightning bugs are doing fine. Others are not.
A survey of 49 of the world’s firefly experts, published Monday in the journal BioScience, has identified the most serious threats to the animals. Habitat loss, in almost all of the regions surveyed, is a problem. Other threats include artificial light, which disturbs their mating rituals; pesticides, which can harm the insects or their invertebrate prey; and water pollution, for species that have an aquatic stage.
The report is not a census of the world’s firefly population. But it is “the very first time that we’ve gathered information — this is based on expert opinion — about what the most prominent threats are to the fireflies in different parts of the world,” said study author Sara M. Lewis, a biologist at Tufts University.
“For the last decade or more, people have been anecdotally reporting that they’re not seeing fireflies where they used to,” Lewis said. “Good census data over the past few decades” exists for some species, such as Malaysia’s synchronous fireflies and the common European glowworm, Lewis said. “We know that those populations are, in fact, declining.”
Elsewhere, however, firefly literature remains “kind of obscure,” she said, and the research community is relatively small.
This poll of firefly experts was the “next best thing” to traveling back in time to count firefly populations, said University of Florida entomologist Marc Branham, who was not a member of the research team. He has been told many anecdotes of missing fireflies. And often, he said, they’re believable. Fields once full of flashing insects “are so obvious, in a sort of a sad sense,” when the light vanishes, he said.
“One of the things we’ve kind of taken for granted is that fireflies will always be here,” said naturalist Ben Pfeiffer, founder of the nonprofit Firefly Conservation & Research organization and one of the firefly experts who was surveyed. “And we’ve been terribly wrong about that.”
In 2018, the International Union for Conservation of Nature created the Firefly Specialist Group, co-chaired by Lewis, to determine whether certain firefly species should be listed as threatened or endangered. “That’s something we’ve never seen happen for a firefly species,” Fitchburg State University biologist Christopher Cratsley said. Cratsley was not a member of the study team.
The survey, Lewis said, represents a first step in that process. She cautioned that “we don’t know what the relative importance of these threats to fireflies are. We only know the ranking of what firefly experts believe.”
A contrast in firefly health is evident in the eastern United States. There, Photinus pyralis -- also known as the big dipper firefly, for the dipping J-shape path the beetle makes as it flies — remains a common sight at dusk. “It’s a very weedy species. It’s a habitat generalist,” Lewis said. These fireflies swoop over rural meadows and the streetside gardens of the District. “We’re lucky that we have some fireflies that are probably going to be just fine.”
Due east of the nation’s capital, however, the situation is dire for the Bethany Beach firefly. That insect, which produces bright green double-flashes, lives only in Delaware’s coastal freshwater wetlands. Residential development has imperiled the species, and in May the Center for Biological Diversity and the Xerces Society for Invertebrate Conservation petitioned the Interior Department to add the firefly to the Endangered Species List.
Artificial light at night can confuse the fireflies and glowworms that use bioluminescence for mating rituals. In the United Kingdom, female glowworms climb up to perch at the tips of vegetation and glow to attract males. “A number of different studies have shown that artificial light in a glowworm habitat actually prevents the males from finding the females,” Lewis said.
Background illumination can also mess up the animals’ sense of timing. “I’ve seen fireflies in New York City that begin courting at like 4 in the afternoon in the summertime, which is not the right time,” Lewis said.
In countries such as Japan, Malaysia and the United States — particularly where there are synchronous firefly displays, like the Smoky Mountains — firefly tourism attracts about 200,000 visitors per year, Lewis estimated. Well-meaning tourists may not realize they are endangering the animals they wish to appreciate. “If you have a lot of people who are tromping through the firefly’s habitat, they’re stepping on larvae” or flightless females, she said.
Some places have taken precautions against trampling feet and have developed firefly sanctuaries with elevated footpaths. A recently enlarged firefly preserve in New Canaan, Conn., is the first of its kind in North America, Cratsley said, at least as far as he was aware.
“The land trust was immediately adjacent to a large mansion — a beautiful home,” he said, of his visit in summer 2019. “But you could go from being surrounded by fireflies to a complete dead zone, of nothing, in that manicured lawn.”
The firefly experts encouraged people to join monitoring groups such as Firefly Watch, a citizen-science project run by Mass Audubon that has partnered with Cratsley, Lewis and other researchers.
“If people are willing to spend five or 10 minutes each week out in their backyard figuring out what kind of fireflies they have and then counting their flashes,” Lewis said, “we think we could begin to gather the kind of long-term data that we need to figure out what species are in trouble.”
Where Light Pollution Is Seeping Into the Rural Night Sky (click here)
Submitted by Barry Buschow
Commercial pumpkin growers routinely rent honey bees so they have enough insects to pollinate their crops, but a new study published in the Journal of Economic Entomology suggests that wild bees can do the job for free. The three-year study found that wild bumble bees and squash bees could easily handle the pollination required to produce a full yield of pumpkins in all of the tested commercial fields, according to Carley McGrady, the lead author of the study.
The pumpkin study was part of a broader initiative, called the Integrated Crop Pollination Project, or Project ICP (http://icpbees.org/), which was headquartered at Michigan State University and funded by the U.S. Department of Agriculture’s Specialty Crop Research Initiative. To read more, click here.
by Jeff Stehm
I just watched a webinar on a fantastic new macroinvertebrate identification and citizen science training site – Macroinvertebrates.org! This site, developed under a National Science Foundation grant, took 3-years to bring to life through the efforts of a multi-disciplinary team of scientists and educators. Over 150 macroinvertebrate species of the eastern United States are listed on the site. Identification is facilitated by the over 800,000 high-resolution and expandable images taken of each species as well as the expert content and annotations developed, including key identification features and pollution sensitivity.
The website development involved a set of partner organizations that helped define identification problems and needs, tested the website design and functionality, and participated in research on how citizen scientists learn observational identification tasks. The website has about 5,000 visits a month and surveys indicate that over 90 percent of trainees and trainers come away with greater confidence and accuracy in their identification capabilities and teaching methods.
The website is packed with information, various stunning and expandable views of each organism, printable resources, including a training manual and identification sheets, an informative blog, and other resources. So, check it out! Fantastic and a must see! www.macroinvertebrates.org. Click here for website quick start guide.
For the more ambitious, check out the Taxonomic Certification Program
of the Society for Freshwater Science at https://stroudcenter.org/sfstcp/
By Elizabeth Pennisi, Science Magazine, Oct. 24, 2019 , 2:00 PM
Earthworms are the unsung heroes of the planet’s ecosystems: Unnoticed below our feet, they grind up soil and dead matter, recycling essential nutrients and moving air and water deeper into the ground. Without them, soil health would suffer and plant productivity would falter. Now, for the first time, researchers have mapped where these humble invertebrates live, identifying wormy hot spots around the globe. The project, which pooled earthworm data from more than 140 scientists and 6900 sites, has cataloged hundreds of species and revealed trends about where each plies the soils—and under what conditions they thrive.
“The results … provide a comprehensive global perspective on one of the most important animal groups,” says Stefan Scheu, an ecologist at the University of Göttingen in Germany, who was not involved with the work. Scientists can now start to come up with conservation plans for worms and other organisms that integrate life above and below ground, he adds.
During the 1800s, intrepid explorers collected and cataloged many of the world’s plants and animals, providing range maps for different species that launched further study. But that wasn’t true for subterranean life. “We’ve been lacking basic information [for a long time] about what earthworms live where,” says Noah Fierer, a soil ecologist at the University of Colorado in Boulder.
So, soil ecologist Helen Phillips from the German Centre for Integrative Biodiversity Research in Leipzig and her colleagues contacted all the earthworm researchers they could track down to ask for data about the animals living in their study sites. Ultimately, 141 scientists provided numbers and species names from more than 6900 sites across 57 countries. “There was about three times as much data as I was expecting,” Phillips says.
Compiling and analyzing those data, many of them in different formats, must have been a challenge, says Katalin Szlavecz, a soil ecologist at Johns Hopkins University in Baltimore, Maryland. For example, earthworms have been studied long enough in Europe that most of the species are known. (The United Kingdom has 33 kinds.) But in the tropics, “Every time they dig a hole, they find a new species of earthworm,” Phillips says. And that uneven amount of study had to be taken into account to use the data effectively.
She and her team evaluated the data to make sure they were as comparable as possible from site to site, and then used computer modeling to generate their global map. They were surprised when their analysis showed that temperature and rainfall seem to have a greater influence on where earthworms do best than soil type, they report today in Science.
“It’s surprising that soil properties weren’t the most important driver,” says Tami Ransom, a community ecologist at Salisbury University in Maryland. Szlavecz, too, was astonished how little soil type mattered. The effects of temperature and rainfall suggest climate change will have a far greater influence on below-ground life than expected, they say. Consequently, life above ground might also be affected in ways not previously anticipated.
The distribution of different earthworm species was also surprising. When it comes to life above ground, the tropics have the greatest biodiversity. But underground, these constantly warm regions are far less diverse, at least at a local scale: The rich soils of Europe, the northeastern United States, the southern tip of South America, and the southern regions of New Zealand and Australia seem to have more earthworm species in a given area. Those temperate zones also host more earthworms overall, according to the model, with up to 150 per square meter versus just five per square meter in the tropics.
It’s vital to know what earthworms exist where, says Kevin Butt, an ecologist at the University of Central Lancashire in the United Kingdom who was not involved with the work. That’s especially true, he adds, “as we are in an era when large global upheavals are at play.”
Posted in: Plants & Animals doi:10.1126/science.aaz9771
by Jeff Stehm
Halloween is approaching and it’s time to consider that ubiquitous symbol of the haunted house – the spider’s web. We often see spiders as scary or a nuisance, and their webs as something that must be brushed away, but in fact spiders and the webs they weave are one of the complex wonders of nature.
Dating back almost 400 million years ago, spiders are among the most diverse of terrestrial predators. At least 48,200 spider species, and 120 spider families have been recorded by taxonomists. While we typically associate spiders with webs, not all spiders spin webs (see Wolf Spiders) or use the silk they produce for webs (see Jumping Spiders). Species that produce silk, but not webs, may use silk in several ways: as wrappers for sperm and for fertilized eggs; as a "safety rope"; for nest-building; and as "parachutes" by the young of some species.
But webs are what we notice, so let’s learn a bit about web materials, web structure, web functions, and the evolution of webs.
Have any of you been seeing swarms of dragonflies in your yard and pastures the past few weeks? This is the first time my wife and I have experienced this phenomenon of nature. I’ve discovered that dragonflies do have a swarming behavior, although scientists aren’t sure why. Two types of swarms exist. The migratory swarm where large masses of dragonflies migrate, flying at higher altitudes. Some of these migratory swarms have been dense enough to show up on weather radar.
The other type of swarm that we experienced is a static feeding swarm, where several hundred dragonflies swoop low over a lawn or pasture in figure eight patterns catching bugs. The numbers were thick enough in our yard that all I had to do was swing my butterfly net and bam! I had a dragonfly! She was kind enough to pose for the photo below before flying off to rejoin the group.
The iNaturalist group identified her as a Common Green Darner (Anax junius) which is one of the largest dragonflies; males grow up to 3 inches in length and have a 3-inch wingspan. They also migrate great distances from the northern US to south into Texas and Mexico. Neighbors around us have been observing similar swarms.
If you interested in further information on this phenomena, I found a great website https://thedragonflywoman.com run by an aquatic entomologist, Christine Goforth from the University of Arizona. Her website contains a wealth of information on dragonfly swarming as well as a page to report a swarm siting as part of a citizen science project she is running.
Her descriptions of static swarming matches what I’ve observed – the dragonflies typically appear near dawn or dusk (dusk in my case) because it is thought that dragonflies can see their prey better when the sun is low on the horizon. They appeared very suddenly, fly figure eight patterns over our yard for about an hour, and then are quickly gone. The swarms we have witnessed often start around 5 pm and go until about 6 pm when the sun dips below the trees. Dr. Goforth indicates that dragonflies are attracted to large groups of prey organisms. Once the prey numbers drop or they become less active (e.g. as it gets darker), the dragonflies move on. If the prey returns the next day, the dragonflies likely will too. So far we’ve had about 3-4 evenings of dragonfly visits to our yard.
Dr. Goforth says that the swarming behavior is fairly common in many different species of dragonflies, but the chances of a single person seeing more than one or two swarms in their lifetime in a single area can be quite low. The conditions have to be just right for swarms to occur, perfect for both a large number of prey insects and a large number of dragonflies to exist in the same area at the same time.
I count myself lucky to have had a once-in-a-lifetime experience. What marvelous creatures.
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