How long to butterfies live in Mexico, dumb question?

[jen]

I have a question that might sound dumb. I have been rearing monarchs all summer, most from eggs. I heard the butterflies only live for a few weeks. The later season butterflies then make their migration to Mexico. How do those butterflies live for so long there? I know it is warmer, But why do the ones on the east coast only live for such as short time? Can someone explain to me the life cycles of the migrating butterfly? I'd really appreciate it!
Jen

[Jim]

There are two kinds of generations of monarchs...the spring/summer reproductive generations (4-5 of these in Kansas from about May-September) and the migratory generation (only one per year).

The entire life cycle of a monarch from egg to adult is about one month and during spring/summer as adults monarchs live about three-six weeks, which is pretty standard for most insects at this time. In the fall a single migratory generation emerges across the eastern U.S. and into Canada that will make the migration to the overwintering sites in central Mexico west of Mexico City. Some of these butterflies will travel over 2,000 miles and it will take them a lot longer than a few weeks to get to their destination. It turns out that these migratory monarchs may live up to seven-nine months. Wow!

So how do they do it? Well, for starters they are non-reproductive (mating is very energetically expensive or such a small organism). Also, most of their flight during the migration is not powered; that is, they are not actively flapping their wings. Rather, they are doing a lot of gliding and soaring, riding thermals (columns of warm rising air) to climb to an altitide of sometimes several miles and then gliding long distances - just like some birds and glider pilots do.

The location of the overwintering sites offers the perfect microclimate for the monarchs - with temperatures dipping down into the 30s at night and warming up to the 70s or 80s during the day. Millions of monarch butterfllies spend much of their time clustered in the trees, remaining relatively inactive until warming up enough during the day to leave the roosts in search of water and/or nectar. Then it's back to the roosts in the evening.

So if these migratory monarchs are non-reproductive, how do we get new monarchs in the spring, you ask? Good question! Right around Valentine's Day oddly enough the monarchs become reproductive and begin mating as they leave the roosting areas to head back north. The females will then lay their eggs on milkweeds in the southern part of the U.S. before they die. These offspring will mature into adult butterflies that will continue to move north (reproducing along the way) to eventually repopulate the rest of the continent - all the way up to the northern limit of milkweed in southern Canada.

So, whereas the migration south consists of a single generation, the return trip will take several generations to complete. You can think of the monarchs that make the trip to Mexico then as the great-great-great-grandchildren of the monarchs that were there the year before. There may be one too many or too few "greats" in there but you get the picture - the migratory monarchs are separated by several generations, making their annual trek to the same locations year after year all the more amazing.

Make sense?

[jen]

Thanks, Jim , that really does clear things up.
So, It wasn't a dumb question after all?
Jen

[RozieMozie]

Jim thts amazing ... i've been wondering the same thing ... ty very much for clearing tht up!

[Fishslime]

with a slight NW wind over the Blueridge Mtns in PA 40 75 - 9/4/06 saw 4 monarchs heading for Mexico in 1 1/2 hours - last fall Sept 18 in two hours saw 28 monarchs - - time will tell - question - will the cats that are on the milkweed speed up the process into adulthood? the milkweed is yellowing and dying on the local farm - saw 50 plus cats without trying too hard -question- would moving these cats to a higher/warmer area(green milkweed) give them a better chance of surviving??? question - what is the cut off temperature for survival ?? thanks for any info - I'll research my questions now - getting lazy I guess

[butterflymama24]

we took in two late cats in early october...My daughter found them while taking a hike with her class and the teacher was surpise too. they took em into the class and I went out in search for the best milkweed that could be found. and the teacher took them home and reared them until pupa stage and then when they emerged I took them in...they survived here in my house for 55 days... but it wasnt the longest I had taken care of a butterfly like the cripple ones that emerged I cant see them dying in pain...but I take care of them but since feeding them... my one daughter loves helping with the cripple or deform ones ...but she lived until she was 62 days....

butterflymama24

[Teresa]

Thanks Jim, thats a great discription. I didn't realize that they became active during the day while in Mexico. Makes sense tho, they need to eat. I thought they just stayed dormant.

Butterflymamma, thats great of you to keep the crippled ones alive like that. I always feel sorry for them and put them in the frig and then to the freezer.

[Mona Miller]

with a slight NW wind over the Blueridge Mtns in PA 40 75 - 9/4/06 saw 4 monarchs heading for Mexico in 1 1/2 hours - last fall Sept 18 in two hours saw 28 monarchs - - time will tell - question - will the cats that are on the milkweed speed up the process into adulthood? the milkweed is yellowing and dying on the local farm - saw 50 plus cats without trying too hard -question- would moving these cats to a higher/warmer area(green milkweed) give them a better chance of surviving??? question - what is the cut off temperature for survival ?? thanks for any info - I'll research my questions now - getting lazy I guess

I was on the top of Hawk Mt. in PA near Harrisburg this fall on October 28. It was about 40 degrees down in the parking area and much colder with the wind up on the mountain. We actually saw a Monarch migrating much lower than the hawks. I was totally surprised that it could even fly at those temps. I know in Mexico that the night time temps can drop down to 35 and even lower with storms. Apparently, 25 is the lowest I have heard of Monarchs being able to survive, but not for too long and not if they are wet. At that temp there would not be any activity. Apparently, even with temps as low as 25 it is a bit warmer layered together under the cover of the trees.

I had a friend this fall that collected some caterpillars after a hard frost and they made it. She raised them, we got a friend to give them a ride down to Virginia Beach where usually they don't see hard frost or snow.