Drawing of a ballooning spider on a clover leaf. From B.J. Kaston’s How to Know the Spiders
“Fairies with gossamer wings, bring forth beauty, grace and joyful things.”
Dallas television and radio stations yesterday were obsessed with reports of strange white silk dropping out of the skies over north Texas. Although this is an annual phenomenon, it always seems to catch many unawares.
The silken strands falling from the skies are spider silk. The English called it “gossamer”, the Germans call it the “flying summer”. Whatever you call it, this silken shower is evidence of a massive spider dispersal that takes place every year, especially in the fall.
The ability to travel and disperse is a requirement for success in both the plant and animal world. Animals that want to succeed must have the ability to discover new habitats and new lands. Spiders, with their short legs, would seem to be at a disadvantage in the distance travel game, except for one trick.
Baby spiders and many of the smaller spider species, have become especially adept at aerial travel. It’s called ballooning, and it is basically hang gliding for the eight-legged. Ballooning spiders first climb to some high precipice (the top of a grass stem, tree branch or fence post, say) before turning skyward its silk-spinning organs (spinnerets, usually located on the tip of its abdomen). As wind currents catch the emerging strands of silk, the tiny spiders are caught up into the air and hurtled to destinations unknown.
As these silken parachutes are blown about on the wind they adhere to other spider parachutes and eventually form clumps large enough to be seen by even casual observers. Hence the gossamer that everyone is wondering about right now.
Ballooning is a natural phenomenon, something I found myself explaining to reporters and some in the public shortly after 9/11/2001 when everyone’s thoughts were on terrorism. I recall a rumor at that time that the silk was part of some sinister plot. It took some explaining to calm excited callers and convince them that Al Qaeda was not foisting a chemical (or spider) attack on North America.
The big clumps of silk I see drifting on the winds in the fall serve to remind me that humans are still the minority on planet earth. Imagine the billions of tiny spiders it must take to cover the countryside with so many of these gossamer strands. Hundreds of spiders must be involved in creating just a single visible clump of silk. And this has been happening annually for dozens of millions of years.
So a quick salute to the spiders. May they land in fair places…away from my house.
Spotted wing Drosophila on strawberry. Photo courtesy Bev Gerdeman, Washington State University Extension
As if we needed more insect pests! Now there is a new pest of berries that is spreading rapidly around the U.S. The spotted wing Drosophila, Drosophila suzukii, is a native of Japan and was first discovered in California in 2008. It has spread quickly to berry growing areas on the west and east coasts, as well as Canada, Michigan and the northeast. It showed up in Colorado last year, and the first specimen in Texas was found by a faculty member in the entomology department at Texas A&M earlier this year. Oklahoma discovered SWD in a berry farm in Tulsa this past June, and the pest has been in Louisiana since 2010.
While berries seem to be the most susceptible crop, and Texas may not be considered a huge berry state, the potential for damage here is still significant. Besides raspberries and blackberries and strawberries, the fly attacks peaches, blueberries, plums, figs, persimmons and mulberries. It can also survive on Osage orange, honeysuckle and snowberry and likely other berries native to Texas. It does not seem to be a major pest on tomatoes (all Texas vegetable growers say Amen), though it has been found in tomatoes that have cracked or been injured.
The SWD is similar in size and appearance to those vinegar or fruit flies that come to the bananas in your kitchen. Adult flies are 2-3 mm in length, with red eyes and a tan-colored body with darker bands across the abdomen. Males have characteristic single spots at the leading edge of the tip of the wing and two dark bands made of hairs on their front legs. Females lack wing and leg spots, but are distinguished by a robust, curved, serrated ovipositor (the egg-laying “tail”, visible under magnification). Click here for an excellent identification guide from Pennsylvania State University. For the geekier entomologists and horticulturalists among us, who are interested in a 45-minute lesson on identifying this insect and its damage, see the 2012 webinar by Oregon State University entomologist, Dr. Amy Dreves.
In the backyard, the SWD and its damage is often not noticed until fruit is being harvested. And spraying at this time will not protect the crop, because maggots already are in the fruit.
For more information about this pest, check out some of the many excellent Extension materials listed below. If you find what you suspect to be SWD, follow the instructions on this site for sending specimens in for identification. The best way to get specimens for identification are with an apple cider vinegar trap. Note that photos of rotting fruit will likely not be sufficient to identify this pest. Master Gardeners with an interest in monitoring for this pest in Texas…this would be a great applied research project!
Even the tidiest landscapes can harbor large numbers of mosquitoes, especially yards with shade
If you live in north Texas, chances are that you’ve been following reports of mosquito spraying efforts. You may have heard that in September the risk from West Nile virus usually goes down. However, the latest data shows that WNV risk may a actually be higher now than any time during 2013.
Nevertheless, this is no time to let your guard down when it comes to venturing outside in the evening and at night. According to last Friday’s WNV Epidemiology survey, sent from the Dallas County Department of Health and Human Services to local health officials, the standard statistical measure for West Nile virus risk, the Vector Index, was higher last week than it has been all season.
The Vector Index is a statistical tool that combines information about mosquito abundance and mosquito infection rates into a single number. Preliminary estimates of last week’s Vector Index were higher than any week so far this summer, though still far below last year’s highs.
While this is no cause for major alarm, it shows that we haven’t made it through the virus season yet. Until we get some good rain storms to flush out the standing water pools, along with cooler weather, the mosquitoes really don’t know whether it’s July, August or September. Conditions are still excellent for mosquito breeding and replication of the virus in the local mosquito and bird populations.
So if you’re going outdoors, especially in the evening, early morning or anytime at night, put on the repellent. Put it on your kids and loved ones. It’s the single most powerful tool we have for reducing our risk for mosquito borne disease.
Juliana Rangel Posada is a relatively new Assistant Professor at Texas A&M specializing in honey bees. Last week she was named “Inspiring Latina of the Week” by Latina Magazine. The magazine printed an interview with her that might be of interest, especially to aspiring Latina entomologists.
Congratulations to Julia for this honor. Her arrival at Texas A&M was highly anticipated, as our department had been missing a honey bee biologist for an extended period of time. And bees are an important part of our agricultural economy in Texas. This position is also looked to as a resource by beekeepers throughout the state. Juliana brings energy and enthusiasm to her job as an entomologist and is one of many professional entomologists at work in our department.
A small disclaimer. I have never read Latina magazine before, so this was a bit of an eye-opener for me. I’m not endorse all the racy ads and stories. I’m just reading it for the article.
Anyone who knows me, knows I love books. Especially books with beautiful pictures. And what subject is more beautiful than butterflies?
The book I have most commonly recommend for people interesting in learning more about butterfly gardening is Butterfly Gardening for the South by Geyata Ajilvsgi. Now there’s an updated, Texas version, of her book, Butterfly Gardening for Texas. According to Sarah Gardener at Texas Discovery Gardens, the Gardens will be hosting Ms. Ajilvsgi Sunday, September 8 for a Garden Stroll and book signing.
Admission is free to the butterfly house and gardens, and visitors can enjoy a stroll through our butterfly house and gardens, followed by a Q&A and book signing at 2:30. Books will be available for sale at the Gardens Gift Shop, but you may have to reserve a copy by emailing Sarah ahead of time.
It sounds like a great way to spend a hot summer afternoon, looking at butterflies and dreaming about how to make your garden more butterfly friendly next year.
Fox squirrels are the most common and aggressive squirrel species in Texas.
Squirrels may be cute, and I enjoy watching squirrels in the woods as much as anyone. I’m less entranced, however, by the squirrel cartel currently occupying my backyard.
A few weeks ago, after returning home from an out of town trip, I noticed something wasn’t quite right with the cedar elm tree in my backyard. An entire branch of the tree appeared to be dead. Inspection close to the trunk revealed that the bark had been peeled off, chewed off actually, girdling the entire branch.
I had noticed more squirrels than usual this summer, and have directed more than one oath at squirrels for bark-chewing in the past. On this same tree for the past several winters I had noticed rather severe disfigurement from squirrel gnawing. This was especially galling to me because the cedar elm under attack was one I had planted myself, and which was finally becoming a useful shade tree. This was the first time squirrel hanky panky had resulted in actual death of part of a tree.
It’s enough to drive one to firearms.
I’ve been curious about squirrel damage to trees for many years, having collected pictures of odd damage that seemed due to squirrels. I have occasionally seen unusual scars and fresh damage most certainly due to squirrels. Some of this damage appears almost artistic, with narrow channels chewed in the bark, almost circling branches and trunks, and damage to the same trees that has taken place for years.
View of squirrel damage to large branches on our cedar elm tree in the winter, when damage is most obvious.
Since my recent damage, a client stopped by our office with a picture of numerous dead branches in his tree and with a sample branch showing the same bark stripping that I observed at my home. I’ve also had several calls this summer about tips of branches mysteriously dropping off trees. In all cases the cuts are smooth and at about a 45 degree angle–more squirrel mischief.
If tree damage wasn’t enough, squirrels can cause significant structural damage to homes. Squirrels have at least three times now attempted (unsuccessfully) to chew and scratch their way into my attic. Once inside, squirrels (or any rodent) can contaminate and damage insulation and chew on wiring, much like they chewed on my tree bark. And as a potential fire hazard, squirrels are far from cute.
So why am I, an entomologist, ranting about squirrels? I am certainly no expert on squirrels, but there is a new resource on squirrel management in the form of a webinar conducted last week by Dr. Steven Vantassel, wildlife specialist with the University of Nebraska. This webinar is available online for viewing at https://learn.extension.org/events/1180. Dr. Vantassel addresses the biology and behavior of several species of tree squirrels, as well as techniques for squirrel-proofing your home (and bird feeders), hazing and trapping nuisance squirrels.
For my part, I’m going to use some of the techniques I’ve learned in the webinar instead of the firearm idea. I think that’s a lot safer for everyone concerned, except maybe the squirrels.
Mosquitoes rest in shady areas of the landscape until they begin actively searching for a host
This week I attended the West Nile virus survivors support group, hosted by Dr. Don Read and his wife Roberta at the Medical City Dallas Hospital. The group meets every two months or so and provides a forum for learning about the disease and allowing victims to share their experiences and learn from other people who have been down the same rough road.
This month’s meeting ended up being very moving, hearing the stories of several people who came down with the illness last summer. One woman in her mid-thirties, another man in his fifties, and another older gentleman were all healthy, active individuals who thought West Nile virus was something they would never have to worry about, much less the most severe form of the disease. For each it has been a life-changing experience and one they all said “they would not wish on their worst enemies”.
At the meeting there was good news in the form of a presentation by Dr. Robert Haley, epidemiologist from Southwestern Medical School and Past-President of the Dallas County Medical Society. Dr. Wendy Chung of the Dallas County Department of Health and Human Services, Dr. Haley and several other colleagues recently published an article in the Journal of the American Medical Association documenting last year’s epidemic in Dallas county and offering hope for how to predict future epidemics.
You’ve heard that every cloud has a silver lining. In the case of last year’s WNV outbreak this was certainly true, thanks to Drs. Chung and Haley, and and their team’s hard work. The large number of cases last year (nearly 400, with 19 deaths) allowed researchers to look at disease trends and to generate some statistically strong numbers that, if known at the time, might have prevented many illnesses and deaths.
I wanted to share two of the findings with you and evaluate this year’s situation in light of what was gleaned from 2012. First, the research gave support for use of a relatively new index used to monitor the course of the disease. It’s called the Vector Index (VI) and it is derived from data on the abundance and infection rates of mosquitoes caught by city health departments. Because this number includes both infection rate and mosquito abundance information, it is a more accurate predictor of disease in humans than either measurement alone.
Weekly changes in the Vector Index in Dallas County in 2012 and 2013. Notice how low the 2013 values are in comparison to 2012. Researchers believe that an index of 0.5 or higher is predictive of human outbreaks in the Dallas area. Data and graph courtesy Dallas County Health and Human Services, and special thanks to Dr. Wendy Chung and her team.
The team discovered that the VI is highly predictive of human epidemics, and that a VI of 0.5 or higher seems to precede large numbers of human cases–at least in Dallas. Although numbers of adult Culex quinquefasciatus mosquitoes this year have trended higher than even last year, the rate of mosquito infection has been lower. This is reflected in much lower VI values for 2013, and if Dr. Haley and his team are correct, WNV risk appears to be much lower this year than last year at this time.
The other significant aspect of their work was data showing that dire health consequences of aerial spraying on human populations was a non-event. During the height of the spraying last summer there was no noticeable or statistical increase in either skin rashes or asthma-like complaints reported to hospitals. Officials last year assured the public that aerial spraying would be safe, and the data clearly support that promise.
So while we don’t expect any big West Nile headlines this summer, this does not mean that there is no risk. Mosquitoes and WNV are nothing to sniff at, and all it takes is a bite from one infected mosquito to change your life. Personally, I’m staying inside more this summer in the evenings, and when I do go out, even for a few minutes, I spray myself with OFF. I find that the only time I get bitten when wearing OFF, is when I’ve missed treating an area of skin (I react to most mosquito bites and know when I’ve been bitten. Not everyone knows if they have been bitten). Be sure to use repellent, and continue to police your home and environs for mosquito breeding sites. And visit the soon-to-be-updated Mosquito Safari website to learn more about what places in your own backyard might be contributing to this summer’s high numbers of mosquitoes.
The ensign wasp lays its eggs in the egg cases of cockroaches.
These tiny braconid wasps do not completely consume their tomato hornworm host before spinning dozens of pupal cocoons over their victim.
Some parasitoids, such as this bethylid wasp are egg parasitoids, small enough to grow up inside a single insect egg.
Ichneumon wasps were among the first parasitoids discovered. They attack caterpillars.
The holes in this scale insect were left behind by emerging parasitoid wasps.
Tachinid flies are another kind of parasitoid. They attack caterpillars and, sometimes, snails.
The words “beneficial” and “parasite” are not normally heard together. But when talking about gardens, and parasitic wasps that attack pests, the word pairing makes good sense.
Many insects in both natural settings and the urban landscape have long been recognized by humans as “beneficial”, as in benefiting man. Predators of pest insects, in particular, have attracted admiring fans, especially farmers. As early as ninth century China, farmers were modifying their orchards to aid the transfer of predator ants for control of citrus pests. By the 18th century birds, ground beetles and lady beetles were recognized as important controllers of pests. Today when someone mentions good bugs, most gardeners quickly point to dragonflies, green lacewings, preying mantids and lady beetles as brave defenders of the garden.
But in addition to these relatively large and showy predators, a whole class of helpful garden insects often are unnoticed, unappreciated, and (sometimes) abused. They are the beneficial parasites, or more correctly, “parasitoids” of the garden. In nature parasites usually only weaken or sicken their hosts. Parasitoids kill and actually consume their prey. Unlike predators which are highly mobile and consume multiple prey, parasitoids are not very mobile (in the immature stages) and typically feed on only one host. The first known parasitoid wasps, called “ichneumons”, were discovered laying eggs on caterpillars and described by anatomists and microscopists in the early 1700s. After the ichneumon larvae hatched, they penetrated and fed on their hosts in a gruesome internal attack. By killing their hosts in this way, ichneumons were found to provide an excellent way to control pests.
We can thank benefical parasites that our gardens are not constantly overrun with pests like these aphids.
Today we recognize hundreds of wasps, flies and (a few) beetles as insect parasitoids. Besides the ichneumon wasps, dozens of other wasp and fly parasitoid families have been discovered. We now know that parasitoid insects tend to be very closely attuned to their hosts, and are often specialized on only one or a few closely related species of prey. Thanks to specialization, parasitoids are usually very adept at finding pests before the pests become abundant. The fact that insect pests rarely take over gardens or landscapes is due, in large part, to the presence of parasitoids working quietly behind the scenes.
As more of the natural landscape is urbanized, gardeners face a challenge. How do we maintain the right environment to preserve and protect the natural hide-and-seek relationship between parasitoids and predators and their prey? If we ignore the needs of beneficial insects, we can expect pest problems to become more frequent and more severe.
It turns out that parasitoids can do well in urban landscapes and gardens when provided with food and shelter in the form of a diverse landscape–especially landscapes with native plants. For more on how this can be done, click here. In addition, parasitoids must be protected from toxic insecticides.
Because of their relatively small size, parasitoids are extremely sensitive to some insecticides. Here are three ways you can use pesticides while preserving beneficial parasites:
Spray selectively. Most insect pest attack only one or a few types of closely related plants. By spraying only the types of plants under attack, you solve your pest problem and give parasitoids other plants to feed and hide on, free from insecticide residues.
Use low impact pesticides. Some insecticides are inherently safer for small natural enemies, either because they break down quickly after spraying or because they are highly selective for the target pest. For examples of low impact pesticides, click here.
Avoid spraying plants, especially those in flower, during the day. Most beneficial insects are active during the day. By spraying at dusk or at night you can avoid spraying beneficials directly.
Parasitic wasps are among the most effective and common parasitoids in the garden, yet few gardeners notice them. These tiny insects lay their eggs either inside or on their host. Once these eggs hatch, the wasp larvae develop on the internal blood and tissues of the host, eventually killing it. Although one parasitoid only kills one host, each female parasitoid lays her eggs in dozens or hundreds of hosts. Some parasitoid wasps only attack one species of pest, so using these insects in biological control programs can be difficult due to the need to choose the right species of parasitoid and know exactly what pest is present. The empty shell of the host left behind after a parasitoid attack is often called a “mummy”.
To see a parasitoid wasp in action, check out this video:
A few bees entering a home usually means a nest is somewhere inside. This colony in a roof soffit likely consists of 30,000 or more bees. The unpredictability of bees means that a normally peaceful nest can turn dangerous quickly.
It’s not that bees are mean, in a human sense. But they do take exception to any people or animals that threaten their nest, or colony.
So what should you do if you are attacked by bees?
Run! Some people make the mistake of standing in place and swatting bees, but this only gives bees more time to recruit from the colony, and results in more stings. Get to shelter as quickly as you can. Get in a car or building that can be securely shut. If you encounter stinging bees and are a long way from shelter, try to run through shrubs or brush to distract the bees. If there is no shelter nearby, keep running until you leave the bees behind. Some bees may pursue victims a half mile or more before giving up the chase.
Don’t be fooled into seeking escape in water. According to the Fort Worth Star Telegram article, after failing to swat and swipe off the bees, the Tarrant county couple tried diving in their pool. “We were trying to stand up in the water but every time we stuck our heads out for air, they would cover us and start stinging us,” she said. “We were trying to breathe and they were stinging us in the face and in the nose.” Water is a poor shelter from bee attack.
Once you’ve escaped the swarm, remove any stingers from your skin as soon as possible. Honey bees are one of the only stinging insects that leaves its stinger in the skin. Left in the skin, the accompanying venom sac will continue to pump venom. Pull the stingers out with a knife blade scraped gently across the skin, or by scraping off with your finger nails.
Seek medical attention immediately, especially if you experience hives, swelling around the throat or face, or difficulty breathing. While an average healthy adult may able to withstand hundreds of bee stings, for people with bee venom allergies even a single sting can be highly dangerous.
Honey bee attacks have received more media attention since Africanized honey bees entered the country in the early 1990s. Africanized bees, while physically identical to domesticated European bees first brought by settlers to this country about 300 years ago, are genetically predisposed to be more aggressive than the European bee. Africanized bees typically have a lower tolerance for nest disturbance, will send more bees out in pursuit of an intruder, and will chase victims further than their European cousins.
All wild bee colonies in Texas should be assumed to be a hybrid between Africanized and European wild bees. Beekeepers usually ensure that their colonies are founded on the more docile European bees, so the threat from domesticated bees is less than wild bees.
All of this is good reason to be wary of any wild honey bee nest in your home or on your property. A licensed beekeeper or pest control professional can help you get rid of bees. For more information, see our publication E-346, Honey bee control in and around homes.
Products that claim to control insects affecting human health must be properly registered and be backed up by data that shows the product really works.
The company claimed that their bed bug and head lice insecticide was invented by the U.S. Army, and that their product was acknowledged by the USDA as the number one choice of “bio-based” pesticides. The company also claimed that the U.S. EPA was warning consumers to avoid “chemical solutions” for treating bed bugs. The problem was that the company’s claims weren’t true.
As a result of false claims and illegal marketing of untested products for bed bugs and head lice, yesterday the Federal Trade Commission issued a judgment and settlement with a Texas-based manufacturer of cedar oil based insecticides. This action was a follow-up to charges filed last fall against another manufacturer of an unproven bed bug treatment containing cedar, cinnamon, lemon grass, peppermint and clove oils.
It’s important to note that the FTC was not saying that these oils don’t work against any insect pests. Many plant based oils do have significant insecticide properties. It’s that the manufacturers had no data to show they worked against bed bugs and head lice, as they claimed. And they made false claims.
You might ask, “what’s so bad about making dubious insect control claims for a supposedly ‘safe’ product like cedar oil?” After all, the U.S. EPA has frequently let the market determine which products really are effective against many pests. And if the product really is safe, what’s the harm of promoting it and letting consumers figure out whether it works or not?
Historically regulators have drawn a line in the sand, and rightly so, for products that claim to control bed bugs, mosquitoes, head lice or other pests affecting human health. If you think you are protecting your or your children’s health by using a product, the federal government has long taken the stance that you have a right to be reasonably sure that the product should work.
The FTC cautions consumers about advertisements that offer quick solutions to bed bug infestations. Consider that if it were easy to control bed bugs with a do-it-yourself product, why would so many people continue to need the services of a professional? And even professionals find controlling bed bugs a challenge. Sad to say, there is still no silver bullet for bed bugs–natural or not.
