Sunday, 12 April 2015

How to help Monarch Butterflies - build a pen for monarch caterpillars and milkweed plants



Monarch butterfly (Photo by Steve Andrews)  

 Monarch butterflies have been facing big problems in America and their numbers have been declining fast. This has been mostly caused by lack of the milkweed (Asclepias) food-plant needed for the caterpillars. Modern farming using Monsanto’s Roundup herbicide has eradicated the plant from fields where it was once common. 

Tropical Milkweed (In Public Domain)


The good news is that a growing number of people have been helping the monarchs increase their numbers again by simply planting more milkweed. Milkweed seeds are easy to buy on the Internet and you can find them by searching on Amazon and eBay as well. Fortunately too, there are species of milkweed that are suited for growing in the different climatic zones of America too.

One big problem that those people who help monarch conservation by cultivating milkweed for the hungry caterpillars face though, is that the larvae will completely defoliate the plants and will eat the leaves, flowers and even the seed-pods. 

Monarch caterpillar (Photo by Steve Andrews)


If not enough milkweed is grown to feed the ravenous caterpillars then many of them will starve or wander away and meet the same fate.

So as much milkweed as possible should be grown and you need a way of helping the plants to regenerate after they have fed the caterpillars. The plants will recover in a surprisingly short space of time if not subjected to more monarch larvae eating them.

Lawrence Chapman, who lives in Tenerife in the Canary Islands, came up with a brilliant solution to this problem. He built easy-to-make pens that can be put on a garden plot where you are growing milkweed.

Monarch butterfly caterpillar pen. (Photo by Lawrence Chapman, used with permission.)


The pens prevent female butterflies from getting to the plants to lay eggs. This means that milkweed plants that have already lost all their foliage to monarch caterpillars can be covered by one of these pens and allowed to regenerate. The pens are simply made using a wooden frame that is covered with gauze mesh.  The finished item is lightweight so is easy to move about in your garden.

Monarch butterfly caterpillar pens. (Photo by Lawrence Chapman, used with permission.)


To build a pen you need: straight strips of wood 2 cm by 1 and half cm, small brackets available from hardware stores (about 1 inch size), a packet of plastic netting, and a staple gun. 

Pen corner showing bracket (Photo by Lawrence Chapman - used with permission).

A recommended size of pen to construct that is suitable for use in the average garden is 1 m long 80 cm high and 90 cm wide.

After the monarch caterpillars you are helping have finished eating enough milkweed, they spin a small silken pad either on stalks of the food-plant or possibly somewhere on a fence, a wall or underneath some item of garden furniture. The caterpillars hang head downwards like inverted question-marks and transform into a pale-green chrysalis after their finals skin change in the larval stage of the monarch’s life cycle.

The adult monarch butterflies will emerge about 10-days to a fortnight later depending on the air temperature where you are.


Jessica Schab releases a Monarch Butterfly


It is a fantastic experience to be able to see the transformation from egg to adult monarch butterfly, and a very rewarding one too because you can take pride in knowing you have played a role in helping the survival of this beautiful winged wonder.

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