Friday Cat-erpillar Blogging: Missing Monarchs

Populations of Monarch Butterflies have been low in West Central Indiana for the past 2 years. 2012 was a drought year with overall low numbers of butterflies during our butterfly count. Only 2 Monarchs were recorded, less than 1 percent of the butterflies counted. In our best year, we counted 111 Monarchs, over 1 in 4 butterflies counted in 2006. This year, few caterpillars have been reported on plants and only a few adults have been reported. Low numbers are being reported nationwide. Last winter, the overwintering population in Mexico was at a low level, measuring about one-fifth of its peak.

Monarch Larva on Milkweed Leaf

Monarch Larva on Milkweed Leaf

What is causing the decline? Poor environmental conditions (drought) across much of the Midwest in 2012 is partly to blame. The host plants of the Monarch, Milkweeds, thrive in moist soils. The drought adversely affected milkweed populations. Changes in farming practices and roadside management may also contribute. 20 years ago, milkweed was common in many agricultural fields with up to 40 plants per acre. New pesticides a more effective in controlling weeds including milkweed. In the past decade, more agricultural land has moved from conservation area to production, decreasing the milkweed population. Milkweed can grow along highways and drainage ditches along roadsides. It cannot survive more intensive mowing practices.

Monarch advocates are suggesting that more areas be managed to produce milkweed and plants that provide nectar for butterflies. This might boost the monarch population. Numerous factors are contributing to monarch population decline, not all of them understood. It is important to monitor the situation so we can be better informed about the extent of the problem. Will we see Monarch Butterflies at our 2013 Butterfly Encounter? Tomorrow will tell.

About jjneal

Jonathan Neal is an Associate Professor of Entomology at Purdue University and author of the textbook, Living With Insects (2010). This blog is a forum to communicate about the intersection of insects with people and policy. This is a personal blog. The opinions and materials posted here are those of the author and are in no way connected with those of my employer.
This entry was posted in by jjneal, Caterpillar Blogging, Environment. Bookmark the permalink.

3 Responses to Friday Cat-erpillar Blogging: Missing Monarchs

  1. Pingback: Queens or Kings Necessary | spokes and petals

  2. Cecilia Hennessy says:

    Would planting milkweed in my backyard help? Any tips?

    • jjneal says:

      Put it in a moist spot in a place where you don’t mow. At my old house, milkweeds used to grow next to the creek and I mowed around them. You can be part of a movement!

      Jonathan Neal Associate Professor and Head Academic Advisor Purdue Entomology 901 West State Street, West Lafayette, IN 47907-2089 USA

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