Stories tagged monarch

Oct
04
2009

Antennas key to navigating during migration

Monarch migration: The antenna is vital to navigating.
Monarch migration: The antenna is vital to navigating.Courtesy L-T-L

Ever wonder how monarch butterflies navigate. They use the sun you might say. The sun is constantly moving, though. Well, maybe a built in clock helps. How important are the eyes compared to the antennas?

To figure out what was important scientists dipped some antennas in clear varnish and some in black paint. The ones with clear varnish had no trouble navigating. The ones with black paint covering their antennas could not.

That not only showed the antennas were sensing light for navigating, it also showed that the sense of smell isn't involved in finding the way, since both paints blocked that ability. USA Today

Learn more monarch migration

The study was led by Dr. Steven M. Reppert, chairman of neurobiology at the University of Massachusetts Medical School. I urge you to visit his faculty web page which explains how his team is using anatomical, cellular, molecular, electrophysiological, genetic and behavioral approaches to more fully understand the biological basis of monarch butterfly (Danaus plexippus) migration.
The incredible detail and depth of their research made me appreciate how understanding one little thing like butterfly migration can lead to better understanding how complex things like the human brain works. This recent paper published in science was titled, Antennal Circadian Clocks Coordinate Sun Compass Orientation in Migratory Monarch Butterflies.

Want to help track monarchs? The Minnesota Zoo is offering visitors the chance to participate in a monarch tagging project. (Data from tagged monarchs helps scientists learn about their amazing migration.)

August 30, 4 - 5 p.m.
September 6, 4 -5 p.m.
(Dates are subject to change depending on the weather.)

Cost is $10 per person. Children under 10 should be accompanied by an adult. Call 952.431.9273 to make a reservation.

Aug
01
2007

Monarch butterfly: Image courtesy The Divine Miss K.
Monarch butterfly: Image courtesy The Divine Miss K.
As with the earlier post this question comes from the handwritten questions people leave for our featured Scientist on the Spot. Not all the questions fall into the given scientist’s area of expertise, but are still good questions, so I’m taking a stab at answering them.

This question is particularly timely: “How many days does it take for a Monarch butterfly to hatch?” Timely not only because the migration of Monarchs to Mexico begins in August, but also timely for me on a personal level as one of my favorite places to visit with my mom, wife and daughter at the upcoming Minnesota State Fair is the butterfly tent! (Which, devoted fairgoers, has moved to east of the grandstand on the corner of Dan Patch Avenue and Underwood Street.)

I am assuming the question is really how long it takes the butterfly to metamorphize from a caterpillar to a butterfly. I ask because the caterpillars themselves hatch from eggs. The whole process, from egg to butterfly, takes four weeks. The eggs hatch after 7-10 days, and the process of hatching from the chrysalis takes around two weeks. The length of these stages is impacted by the temperature – the cooler it is the longer this process takes.

Monarch migration patterns: Image courtesy Monarch Watch.
Monarch migration patterns: Image courtesy Monarch Watch.
Now, here is one of the really cool things about Monarchs, I think. Each adult butterfly lives about 4-5 weeks. But once a year in the autumn there is a "Methuselah generation" which will live 7-8 months – effectively outliving the combined lifespan of their parents, grandparents, great-grandparents, and great-great-grandparents. It is this generation of butterflies that migrates from Canada and the United States to either Mexico (if they are east of the Rocky Mountains) or to the Southern California cost (if they are west of the Rocky Mountains – though this population seems to be shrinking – see an earlier post on this).

It is incredible to me that these insects can make a migration that they have never made before, that their parents never made, their grand parents never made, as well as their great-grandparents, and great-great-grandparents. Bryan wrote a post on some recent research that butterflies, “sych UV information up with a natural clock in their brain. By combining these two bits of information, monarchs are able to determine the angle of the sun and always head due south,” which I think is really amazing.

Thanks for the great question!

May
17
2006

Monarch butterfly: Courtesy Matt Stratton
Monarch butterfly: Courtesy Matt Stratton

The number of butterflies migrating through California has dropped to a forty year low, according to researchers at the University of California, Davis. One-half of the usual species of butterflies have not appeared this season, and other species have been observed in very low numbers. Climate change related to global warming and habitat destruction may be the cause.

Global warming is the increase in the Earth’s average temperature over recent decades primarily attributable to human activities.

Habitat destruction is a change in land use in which one habitat is replaced with another. The plants and animals which previously used the site are destroyed or displaced in the process.

A mild winter in Northern California has caused many species to not end their winter dormancy at the right time. This means that many butterflies emerged too late in the season. The proper climate for breeding was disrupted by a wet spring.

In Southern California, an unusually dry desert left little food for caterpillars of some species to feed on. A late snow in the Sierra Nevada may have killed many insects used for food.

Some species of butterflies that breed several times a year may rebound from these events, but for other species the effects may be devastating for up to a decade.

Read the original press release here.

May
05
2005

Every winter Monarch butterflies head south to Mexico to avoid cold temperatures.

monarch butterfly on a branch
Want to learn more about Monarchs and other butterflies? Visit the Science Museum's Monarchs and Migration website

But how in the world do they know how to get there? Well, they don't follow Highway 35, that's for sure. It turns out that monarchs can detect the sun's ultraviolet (UV) rays even when it's cloudy out. (UV rays are the part of sunlight that causes sunburn.)

Up until now we didn't know how butterflies used this UV information to fly south. Researchers led by Steven Reppert at the University of Massachusetts Medical School ran some monarchs through a flight simulator and discovered their secrets. It turns out that monarchs' eyes are very sensitive to UV light. They synch this UV information up with a natural clock in their brain. By combining these two bits of information, monarchs are able to determine the angle of the sun and always head due south. Sailors used a similar method (a sextant) to navigate around the world before the invention of compasses. Monarchs can do the trick all by themselves, though.

Do you think you could walk due south, from Minnesota to Mexico even on a cloudy day?

Some tagged monarchs have travelled more than 265 miles in a single day! Not bad for an insect...

Journey North and Monarchs in the Classroom also have cool websites (complete with projects and "Citizen Science" opportunities) about the annual Monarch butterfly migration.