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West Nile Virus: A small list of mosquito predators for the Dallas area

This list is not comprehensive and will be updated as I find new information.  Nothing listed is 100% effective (as in, “kills every single mosquito”) and everything on the list does eat things other than mosquitoes (which might be a problem if your bats are eating all your dragonflies.)  This list is simply a “starting point” to consider.


Predators of adult (flying) mosquitoes:

Note: predators of adult mosquitoes are general insectivores, which means they will also go after the things that eat mosquitoes.  They should not be viewed as a first layer of defense, but as a second (“backup”) layer of defense:

* bats
* chimney swifts
* swallows
* flycatchers (these are migratory and don’t live here all year around)
* Nighthawks and nightjars
* dragonflies
* damsel flies
* spiders
* toads
* frogs


Larva predators

Note: these are the most effective ones against mosquitoes

* gambusia (minnows)
* Predaceous diving beetles
* copeopods
* dragonfly nymphs
* damselfly nymphs
* bacillus thuringiensis (bacteria, available at home improvement stores.  Very eco-friendly but not long-lasting)
* tadpoles (many frog species)
* backswimmer (insect)
* tadpole shrimp


This report suggests that mosquitoes can “taste” when a site has gambusia minnows and will not deposit eggs there (indirectly controlling WHERE eggs are laid).


And for those who like hard science, a very readable study from Europe on “who eats whom in a pond.”


Something that I continue to look into is “what nectar sources do mosquitoes favor?”  The adults use nectar (blood is only used by females and only when they are ready to lay eggs) as a rule — surely there’s flower shapes that they can’t utilize well.  Reduce the food for adults, and you help reduce the population.


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Defining Dallas: Does Drought Increase Acid Rain Effects?

     Acid Rain was one of the big “bugbears” of my youth — a keyword that caught our attention along with pictures of dying trees.  Legislative action in the 1970’s (reinforced by the Clean Air Act) helped turn things around, and ponds and lakes began recovering.  Acid rain was an issue of the past.


We’re in the middle of a second year of drought here in Texas, and the drought monitor shows that we haven’t had enough rainfall to make up for the deficits. I’m watching the ponds dry up again at Trinity River Audubon Center and am setting up some trees as monitoring stations to start making measurements of just how much trouble the vegetation is having.  If the research published in the journal Water Resources Research, Charles Driscoll of Syracuse University and the National Science Foundation’s (NSF) Hubbard Brook Long Term Ecological Research (LTER) site in New Hampshire is indicating a trend, counties suffering from the drought are soon going to be hit with a double whammy when the rains return.

Photo of a stream with boulders in the streambed.

New England’s ecosystems have rebounded from the disastrous situation of the 1950’s only to be faced by issues caused by today’s higher atmospheric carbon dioxide level and its atmospheric fallout.  Warmer temperatures and an increase in carbon dioxide is changing the pattern and quality of water in forested areas, and a model used by Hubbard Brook predicts that snowfall at Hubbard Brook will begin later in winter, snowmelt will happen earlier in spring, and soil and stream waters will become acidified — and we’re back to the Acid Rain problem again.

Here’s the kicker: In scenarios that look decreases in summer soil moisture due to shifts in hydrology (as in, “drought”), the end result is further acidification of soil and water.

Last year, I saw crusts of salt along the ponds here in Dallas as they dried out.  I’m not seeing that yet, but the report suggests to me that it might be a very good time for an increase in citizen science monitoring of our waterways.  Fellow Texans interested in this can contact the Texas Stream Team.  I’ll be getting training for this sometime in the near future, so it may be added to the Trinity River Audubon Center’s Third Thursday Science Programming.

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Related Websites
NSF LTER Network:
NSF Hubbard Brook LTER Site:
Science, Engineering and Education for Sustainability NSF-Wide Investment (SEES):




Facebook Helps Researchers See How Friendships Form

An interesting press release which correlates loosely to something I’m studying.  For me, an important “take away” lesson is that unless you are a public figure to some degree (a web comics artist, for instance), your circle of friends and acquaintances will all tend have very similar opinions about many things.


This is why so many people tend to think the whole world shares their view about everything.


T’aint so…

Long-term study analyzes social selection and peer influence in online environments

Image showing college students' tastes and social networks on Facebook.

College students’ tastes and social networks on Facebook.
Credit and Larger Version

December 19, 2011

New research funded by the National Science Foundation and published this week in the Proceedings of the National Academy of Sciences by three Harvard University sociologists examines how we select our friends and the role that friendship plays in transmitting tastes and new ideas.

Relationships are basic building blocks of society, and understanding who befriends whom can therefore provide insight into patterns of social segregation, mechanisms for the reproduction of inequality, social support (including mental and emotional health), and access to job opportunities. Some have even viewed these relationships as a means to influence behavior whether to control obesity or target advertising. But is it really that easy, even on the Internet, to make friends with people who have different cultural upbringings, different interests, different backgrounds and different tastes in movies, music and books?

“At the end of the day, we have to ask ourselves how much of online interaction–and friendship formation in general–really is about reaching out to new people and learning about totally new ideas and perspectives that don’t really interest us,” said Ph.D. candidate and coauthor Kevin Lewis, “as opposed to seeking out those perspectives and ideas we already like?”

Lewis and another Ph.D. candidate, Marco Gonzalez, coauthored a paper along with principal investigator Jason Kaufman, which used Facebook to examine whether people become friends because they resemble one another or whether people become more like their friends over time.

They found people’s individual tastes influence the formation of friendships much more than a person’s individual, pre-existing tastes spread through his or her friendships.

“One feature of Internet relationships that is particularly amenable to our research question is the extent to which it fosters users to communicate their own taste preferences and consumption patterns,” said Kaufman. “Such self-presentation is a normal part of everyday life, but sites like Facebook encourage and codify it.”

Using a unique, four-year, longitudinal study based on the Facebook activity of a cohort of college students, the researchers studied whether tastes in music, movies and books spread among friends over time. They discovered that students who like certain kinds of music and movies are indeed more likely to become friends on Facebook, but the “diffusion” of tastes through friendship ties was extremely rare.

Friends befriended others with whom they shared interests; they did not generally adopt new interests because had developed new friends.

The finding challenges other, recent, highly-publicized research about the importance of peer influence.

“Given the prior research on social epidemics, we found the nearly complete absence of peer influence effects to be rather striking,” said Lewis, the project’s first author and a fellow at the Berkman Center for Internet and Society at Harvard.

“Some of the prior social epidemic research has also recently come under fire on methodological grounds,” said Lewis. “The researchers may be finding so much peer influence because the kinds of models they are running aren’t appropriate and they are misinterpreting their findings.”

“Though many prior studies have attempted to disentangle these two mechanisms [selection and influence], their respective importance is still very poorly understood,” the researchers write in the report “Social Selection and Peer Influence in an Online Social Network.”

“In contrast, the method we used is basically the first tool that is able to disentangle the two processes in a statistically adequate fashion,” Lewis said.

“Our research is unique in that it uses data on a complete social network of respondents–a cohort of students from the same college,” said Kaufman, “and tracks the evolution of that network over time. Because members of the network were, at the same time, listing what they perceived to be their ‘favorite’ music, movies and books, we were able to closely examine the co-evolution of both their social networks and their cultural tastes.”

Then, using state of the art statistical methods, the researchers were able to tease apart the contrasting effects of selection and influence. And they also discovered that simple generalizations don’t always hold. For example, the role books played in friendship formation was different from other forms of media.

The researchers found tastes in books don’t seem to influence Facebook friendship formation in the same way as tastes in music and movies.

Watching a movie and listening to music are things that can be done with peers, allowing opportunities for social interaction, bonding and meeting new people, but reading typically is a solitary pursuit.

But if a student’s friends liked “indie/alt” music, the student was less likely to adopt the same tastes, presumably because the value of “indie/alt” taste comes precisely from being the only person among one’s friendship group that likes it.

In contrast, though, the researchers also found that students whose friends expressed tastes in “classical/jazz” were significantly more likely to adopt such tastes themselves, so interest in some musical genres diffused among friends. With these few exceptions, though, preferences did not generally appear to be “contagious” among Facebook friends over the duration of college.


Media Contacts

Bobbie Mixon, NSF (703) 292-8485

Program Contacts

Regina E. Werum, NSF (703) 292-2690

Principal Investigators

Jason Kaufman, Harvard University (617)-461-8389


Kevin Lewis, Harvard University (617) 461-8389




Science of Shopping: Cameras & Software That Track Our Shopping Behavior

Video cameras — it seems like they’re everywhere these days.  From cell phones to traffic cameras to in-store security systems, it seems like we spend most of our day in the glare of the camera’s eye.  I find myself on the fence in this particular debate — I don’t like the idea of the invasion of privacy, but I do like the idea that if someone comes along and smashes out my car window that some camera can get evidence to catch the thief.  And as an anthropologist, the idea of using cameras for marketing research is old hat — the difference being that we’d have to sign the person up and notify them they were being watched.

But now store owners can use footage to decide what products are attracting customers to the store and what keeps them coming back.  The data they’re looking for is deeper than what can be pulled from cash register receipts.   That database won’t tell you if customers are walking past and pausing and returning several times before selecting something else (which means there’s something they find appealing) or just strolling past without more than a glance — and those two behaviors may determine where a product gets placed or whether the store continues to buy it.

With support from the National Science Foundation (NSF), computer scientists Rajeev Sharma, Satish Mummareddy and their colleagues have developed software that analyzes video images from overhead cameras to study shopping behaviors of store customers.  The software then creates maps of the store’s traffic patterns that show which areas are heavily traveled and which are ignored.  It also times how long a person stands contemplating an item before they buy or they walk off.


In order to preserve privacy, Sharma says that the company’s cameras are positioned directly above the aisles and that they set the picture resolution low so that all shoppers remain anonymous.  Because they’re not looking at details (like what type of clothing the person is wearing and so forth), behavior pictures emerge.  For instance, people prefer to shop on wider aisles and avoid narrow ones.  Brand loyalty, once a strong factor in shopping, doesn’t carry as much weight now that people are worried about the economy.


One interesting and amusing outcome is that some of the popular stereotypes are supported by the findings.  Women DO take a lot longer to shop than men (so that old joke about men hating to go shopping with their wives because it takes forever has some truth in it.)




Do Dyslexics Hear Words Differently?

Dyslexia as a diagnosis is a broadly defined learning disability which includes difficulty in being able to recognize letter shapes and groupings, making it hard for the person to read and spell fluently and to understand what they’re reading.  A new study from MIT probes farther into the observation that dyslexics may also have trouble understanding “phonemes” — subtle differences in the sounds of human language by observing how well dyslexics and non-dyslexics are able to recognize the voices of people speaking either the listeners’ native language of English or an unfamiliar foreign language, Mandarin Chinese.


What they found supported the idea that the problem isn’t actually about reading.  One of the problems about theories on how dyslexia is produced is that dyslexics learn to speak their native language at the same rate that the rest of the population does.  The current thought is that the dyslexic can’t “tie” the phonic symbols (which they struggle through) to the actual sounds of the words — but doesn’t explain why dyslexics often have trouble following conversations when there’s a lot of background noise.


The new research suggests that the problem of dyslexia may be involved in the ability to distinguish different properties of speech — in other words, may learn to understand the difference when their mother says the words “pin” and “pen” to them — but may not be able to tell the difference when I say it to them.


For the full National Science Foundation article, click this link


Field Research