Thursday, June 17, 2010

The Monarch Population in June

There is a lingering question about the monarch butterfly population. After devastation in the monarch population over the winter, will their numbers rebound? Previously when numbers dwindled in response to storms or other factors, the following year witnessed a huge increase in population. Will this year see the same?

The winter of 2009 witnessed the lowest numbers of monarch butterflies in both Mexico and California. The Spring reports in the Eastern portion of the United States are very favorable. Monarchs found a rich breeding ground in Texas with abundant milkweed for egg-laying and nectar everywhere from frequent winter rains. In fact, monarchs seemed to hunker down in Texas for awhile, raising speculation of their dynamics as everyone watched the sightings soar on Journey North.  Then when winds and temperatures were favorable, monarchs took off on the move leading to a record number of sightings in May all the way up to Canada.  But the question remained: Were there really more monarchs, or were more people aware of their dilemna and looking for them? Only time will tell. We'll hope for the best.

The news about monarchs in the West doesn't appear as hopeful at first glance. Monarch spotters in California are reporting monarch absence rather than presence. Milkweed locations that usually have "evidence" of monarchs - eggs or larvae - are bare, even though the milkweed is abundant and healthy. While some experts advise patience because of the cool spring, the threads of growing concern are in the air. Hopefully more monarch sightings will be reported as the summer season continues.

Weather affects monarchs. Not too hot, not too cold....sounds like the Three Bears, right? When temperatures are lower than normal or more rain than normal, the monarch life cycle takes longer. When it takes more days to grow as a larvae or pupae, the number of generations can be affected. Studies indicate that monarchs larvae and pupae only grow between 52.7 and 91.4 degrees. When it is above or below this threshold growth ceases and waits until the temperatures rise within these parameters to continue. Look at the weather maps for May and you can see that the East had warmer than usual temperatures, while most of the West was cooler.

Lets all hope that as summer progresses more monarch and monarch larvae will be reported in the West and Southwest. No reports of monarchs yet in June in Arizona. Keep looking! By early July monarchs are usually moving into the state. Keep your eyes open!

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