Monarch Madness

​May is known for the number of birds that travel north for the Summer to nest, but there is another great migration taking place that people may not be aware of. The butterfly migration! Most notably is perhaps the Monarch butterfly who makes a 3000 mile journey from Mexico all the way to the Northeast U.S. and even as far as Canada.

​Differently than bird migration, the butterflies that we see in Massachusetts are not the same butterflies that started the journey in Mexico! There are about four generations of Monarchs that make the migration possible. The butterflies that start the trip will stop somewhere along the way to mate and lay their eggs on milkweed plants. After this, the adult’s journey will end, but their eggs will hatch and once the larvae has gone through complete metamorphosis, they will continue to head north. This cycle repeats until the final leg of the trip, when the butterfly has reached the northernmost point in its journey.

Monarch butterfly egg on underside of Milkweed leaf

Although it takes many generations to make the trip north, in the Fall, it is one super generation that flies the entire 3000 mile journey south over a period of about 3 months. Unlike many insects, Monarchs are not able to overwinter in cold climates, which is one of the reasons they are thought to make this incredible journey twice throughout the year.

Monarchs cover an oyamel fir in Mexico

Once in Mexico, millions and millions of Monarchs huddle together in just a few mountains in the Oyamel Fir Forest. The butterflies rest grouped together in the Oyamel fir trees, also known as sacred firs. These trees create a microclimate for the pollinators so that it doesn’t get too hot or too cold while they are there from October to late March. The forest also maintains perfect humidity for these delicate macroinvertebrates allowing them to stay hydrated and not dry out. The millions of Monarchs roost together in the forest and in the evenings during their migration to trap heat and conserve energy that they need for flying long distances.

​There is not much known about why there is one super generation that seems to dramatically outlive the other generations of Monarchs, or why the butterflies make this long journey. There are, however, many ongoing scientific research projects looking at the benefits of these migrations. Some theories are that the butterflies are following their food sources or that the migration could even be a way to weed out parasites within the population!

For more information on Monarch migration check out these great resources:

• National Geographic 
• Journey North
• Monarch Watch Migration and Tagging
• Pollinator.org
• Monarch Watch Peak Migration Times

​If you are looking to attract Monarchs to your garden this Summer, their number one food source is Milkweed! Adult Monarchs will visit a number of flowers, but they primarily lay their eggs on Milkweed plants and that is the only food source for Monarch caterpillars. For Monarch caterpillars, Milkweed is not only a great supplier of nutrients, but it also fills them with toxins. These toxins are harmless to the caterpillars but will poison anything that tries to eat them! A Monarch caterpillar’s bright colors are a warning for predators to stay away. Animals that have bright colors to indicate toxicity or venom are called aposematic.

Monarch Caterpillar

Common Milkweed in full bloom

Much is being done around the country to encourage the migration of Monarchs as they are one of the key pollinators in the country and serve as a key indicator as to how climate is affecting our planet. Remember when I mentioned that Monarchs huddle in the Oyamel Fir trees to maintain a very specific climate? Any increase or decrease in these temperatures will greatly impact the Monarchs' successfulness. By monitoring Monarch populations, we can start to gain an understanding of how the world is being affected by climate change. When you provide a garden habitat that is helpful for Monarchs you also encourage other pollinators to visit. Pollinators are responsible for 1/3 of the food that is put in front of us! For more ways to encourage pollinator and specifically Monarch friendly gardens check out Monarch Joint Adventure!

​In Massachusetts, we can start to expect Monarchs to show up from now until mid-June, so keep your eyes open for those bright orange beauties! If you have Milkweed in your garden, be sure to monitor the leaves for the different stages of the Monarch's lifecycle!
​