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The Garden Scoop

The Monarch Butterfly

The iconic monarch butterfly (Danaus plexippus) has become somewhat of a poster child for the plight that many pollinators face, and for good reason.  Monarch populations have experienced drastic declines in recent years for a variety of reasons, some which researchers are still trying to explain.  The monarch’s charismatic appearance and large home range, spanning much of the US, has made it familiar to most anyone who has ever caught butterflies as a kid or observed visitors to their flower garden.

It may be the dramatic annual migration of these butterflies that has captivated the public and biologists alike.  Each year, monarchs in our area travel up to 2,000 miles to reach overwintering areas in Mexico, only to make the return trip in spring.  This extreme migration was established during the last of the Pleistocene glaciation periods and has occurred annually since.

Yet another amazing attribute of this butterfly is its lifecycle, as monarch’s have a very specific relationship to milkweeds (Asclepias spp.).  Monarch butterflies only lay their eggs on milkweeds and their caterpillars exclusively feed on milkweeds.  That makes our two dozen species of native milkweeds, which have historically been viewed by most as weeds, extremely important for the monarch’s survival.  This host-specific relationship has further complicated the monarch’s decline since milkweeds are more scant on the Illinois landscape due to extensive weed control efforts, habitat reduction and other factors.

Each year, there are four generations of monarch butterflies in Illinois.  The first generation is born when overwintering monarchs return to lay eggs on milkweeds in late April or May.  Two more generations occur over summer with a lifespan of about 2-6 weeks each.  The final generation, born around September, migrates to Mexico as fall weather begins to cool.  This lucky generation of monarch lives for 6-8 months as it overwinters and travels countless miles on the trip to and from Mexico.  Since the overwintering monarchs do not expend as much energy on reproduction as non-migratory generations, they are able to redirect that energy into survival, extending their life.

The US Fish and Wildlife Service is currently assessing whether the monarch needs protection under the Endangered Species Act.  Their assessment is not scheduled to be completed until June 2019. In the meantime, conservationist, biologists, non-profit organizations, government agencies and others are rushing to implement conservation measures to stabilize the monarch population. 

So, what can you do to help the effort?  One of the most basic things we can do is add more milkweed to our landscaping or preserve areas on our property that support milkweeds.  Roadside ditches are abundant in Illinois and do support a lot of milkweed plants.  Historically, these areas have been regularly maintained with mowing, which impacts both milkweeds and monarchs alike.   However, many organizations, such as IDOT and County Highway Departments, are becoming more aware of the importance of milkweeds and now target their mowing to avoid plants. 

In the wild, monarch caterpillars have a very low chance of making it to butterflies with many studies show the odds at around 10%.  This is not unusual in nature as insect larvae are food for predators.  Given the low odds, many folks have begun collecting and raising the caterpillars in captivity to release the butterflies into the wild after metamorphosis, thus increasing odds of survival.

My family has collected and raised monarch caterpillars for the past few years.  It is a wonderful activity for both kids and adults; nothing beats the thrill of seeing a monarch butterfly float away knowing you helped it along.  Although this activity is a fairly straightforward DIY project, I do strongly recommend thorough research of the process prior to collecting any caterpillars.

Recent research has identified another obstacle for monarchs.  Many butterflies simply cannot find enough food along the migration route.  Although caterpillars feed exclusively on milkweeds, the adult butterflies feed on nectar from flowers.  So, adding flowers to the landscape is a huge help.  Who doesn’t like more flowers? However, many of the non-native flowers we plant do not provide food for monarchs.  This is another reason why planting native species is especially important for the monarch and other pollinators.

As monarchs approach the cusp of being listed as endangered, every little bit we can do to help is much needed.  My hope is that we can someday look back at monarch conservation efforts and tell a story of success, one of a species with an equally dramatic recovery as its current decline.