Lucky Late Monarch

[Schmetterling]

Found a 4th instar on October 17th. During it's time in chrysalis form we had cold days and many frosty mornings here in Southeast Michigan (lat 42.7 long 82.95). Never though that when it eclosed on Nov. 7th, that our temperatures would be in the 60's and due to stay that way most of the week. Found a few blossoms on a butterfly bush that somehow escaped the frost, sipped some nectar and off she went. Now I can confidently say that she is my last one to release for the 2010 season.

[MAM]

It's Nov. 13 and I have two eclosed butterflies. Temps will start dipping into high 30s this tomorrow night and I fear if I release these late bloomers they won't make it. Here in SC we have non migrating species still mating and laying eggs! I've collected dozens of eggs on my milkweed in the past few days.

Question--do I release these two or keep them indoors in my aviary?

Thanks all. I've appreciated the education and comments over the years.

[Mona Miller]

What is your day time temp? Colonies in Mexico range from 40 at night to 60 during the day.

[MAM]

Thanks for your reply. We've had unusually mild weather so I released the butterflies. Butterflies are flying and nectaring here--and laying eggs. I was surprised to go out and discover another dozen eggs today! Temps in South Carolina are getting into the 30s at night later this week and my milkweed is growing scarce. I have 7 large and hungry cats and 13 smaller in varying instar stages, all gathered from my milkweed. It's been a healthy season.

[Mona Miller]

http://www.springerlink.com/content/07627452726w5776/
Biological Observations of Monarch Butterfly Behavior at a Migratory Stopover Site: Results from a Long-term Tagging Study in Coastal South Carolina
Abstract
Like most migratory species, monarch butterflies (Danaus plexippus) must stop frequently during their long southward migration to rest and refuel, and the places where they stop are important for the success of the migration. The behavior of monarch butterflies at migratory stopover sites has never been examined in detail. Here we present results of a long-term study of monarchs at one stopover site in coastal South Carolina where over 12,000 monarchs have been captured, measured and tagged (with numbered stickers to track recovery rates) over 13 years. Only 3 monarchs (0.023%) were recovered at the monarchs’ overwintering sites in Mexico, which is consistent with other tagging studies on the eastern coast. The migration season was longer at this site than at inland locations and monarchs continued to be captured in November and December, when most monarchs had already arrived at the overwintering areas in Mexico. In addition, there were 94 monarchs captured between Jan 1 and Mar 15, indicating that some monarchs overwinter at this site. Of all monarchs captured during the migration season, 80% were captured while nectaring and 10% while roosting. Others were basking, resting, flying and even mating. The sex ratio was male biased by three to one in all behavior categories except those captured mating. Roosting and nectaring monarchs had fresher wings than those in other behavior categories, suggesting that these are younger individuals. There were 13 observations of females ovipositing on non-native Asclepias curassavica during the fall months, which speaks to the potential for this plant to pull monarchs out of the migratory pool. Aside from these insights, this study also serves as an example of the potential that monarch tagging studies have to advance scientific understanding of monarch migration.

[Paul Cherubini]

There were 13 observations of females ovipositing on non-native Asclepias curassavica during the fall months, which speaks to the potential for this plant to pull monarchs out of the migratory pool.

The author of that paper doesn't say what he means when he says: "female migrants were pulled out of the migratory pool." In other words, he doesn't say what would have happened to those female migrants if there wasn't any currrassavica milkweed available for them to lay eggs on. I think it's obvious the females would have ended up searching frantically for milkweed and then end up dying without breeding since the native milkweeds wouldn't be available that late in the year - a horrible fate indeed. But the author seems to be implying that the mere presence of currassavica CAUSED the females to stop migrating and CAUSED them to develop eggs. That's a pretty radical idea considering he presents no evidence that such major physiological changes are even possible in free living fall migrants. I do know that placing potted currassavica plants in and around California overwintering site habitats does not cause hardly any of the overwintering females to abandon the clusters and spend all their time around the plants though a few may hang around for an hour or two.