Milkweed, pollination and butterflies
Many of us have joined the movement to improve the survival of pollinators, which are critical for the production of at least 30% of our food. Their numbers have declined for a few reasons, in particular our destruction of their habitat and overuse of powerful insecticides. While most of us have become familiar with the plight of honeybees, there is relatively large number of other creatures that contribute to pollination of flowering crops.
Many kinds of flowering plants will attract bees, providing them with nectar while festooning them with pollen. When they fly off, the bees share this pollen with other plants, permitting them to grow the fruit we enjoy. When we plant such things as fruit trees, sage and many other flowers, we are receiving their benefits as well as providing a food source of these important insects.
Butterflies are also terrific pollinators, although we tend to think of them primarily as lovely flying miracles. They prefer flowers with a flat area where they can land easily, which is why they are so attracted to lantana and other plants with that kind of flower.
Large colorful monarchs may be the most appealing of butterflies. We often hear about eastern monarchs, which travel enormous distances over three generations. Their western cousins who live around here do not need to go further than California. This is still a long flight for such a small creature. Monarch numbers are also diminishing because of habitat loss and widespread insecticide use. Some, but certainly not all, researchers also believe that pollen from genetically modified crop plants could be another contributing factor.
In order to support the monarchs, milkweed (Asclepias spp.) is becoming a popular addition to a number of home gardens. There are over 100 species of this flowering perennial plant, all native to North America. Unlike some other insects where adults do not feed, the adults of many butterfly species will imbibe the nectar. Milkweed blooms provide a tasty treat to these adults.
The young larvae, on the other hand, are not able to obtain nutrition from the milkweed blossoms. Milkweed leaves are toxic to many varieties of caterpillars, but monarch larvae will chew them and accumulate the toxin. This is the reason so few predators will go after these colorful butterflies.
Since they are perennials, once they have become established, they may live for several years, producing flowers and seeds. Some of the many species are native to this area, and grow very well here in the Mojave. Others are somewhat less tolerant of desert conditions. For instance, swamp milkweed would need more tender care than a desert one. Some appear to survive as long as they are provided with protection from the most intense sunlight.
At Cooperative Extension’s outdoor education center, a dedicated Master Gardener has been hard at work growing a range of different milkweeds. Her efforts will permit us to determine which varieties will thrive in our challenging climate. For more information, call the Master Gardener help line.
Angela O’Callaghan, Social Horticulture Specialist for University of Nevada Cooperative Extension, can be reached by email or call or 702-257-5581.