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Ups, downs for monarch butterflies


A stinging nettle patch produced new caterpillars not seen before, of the Eastern comma butterfly, in September. Others had been around on plants they depend on – pipevine swallowtail caterpillars on Dutchman’s pipe, the variegated fritillary’s on passionvine and violets, and the black swallowtail’s on parsnip. Various other butterflies and moths had tenanted, unseen or unidentified, the property’s native plantings. We appreciate them as the principle food for the young of birds.

Author Douglas Tallamy has identified more than 500 lepidoptera species for whom the native woody plants alone, such as blueberry or gooseberry bushes, ash, oak, basswood, birch and other trees, are host and at least temporary home.

While few monarch butterflies seemed to visit during spring and summer, they became the drama of pleasant sightings, and worries, in the fall. The latter resulted from an overabundance of caterpillars on the milkweed plants they dine on, ingesting a poisonous compound from the sap that will protect them from predators throughout their life cycle.

A gardener in Unicoi reported desperately searching for additional plants for many hungry caterpillars. Jonesborough’s Virginia Kennedy found it unusually challenging to feed and raise more than one hundred of these for her tagging project in the Monarch Watch program. In my yard and garden, three colonies of the common milkweed and a number of its butterflyweed and swamp milkweed relatives seemed insufficient to nourish dozens of monarch-caterpillars mouths.

Had the adults laid too many eggs in the proverbial basket, in hope of getting more generations to take wing on time for the southward journey to wintering oases in Mexico?

Can we hope that the monarchs are rebounding following drastic population declines resulting from chemical-driven agriculture and habitat loss? Are the efforts begun under the Obama administration and its task force on pollinator recovery showing success? Through many new milkweeds and flowers for nectaring planted: in “monarch highways” by government agencies and in connecting corridors by the Nature Conservancy and other environmental groups, and in suburban garden patches by homeowners seeking to help sustain the pollinators and other wildlife?

Yet the monarch’s overall downward trend continues, and climate change may have its effect. By late August, most of the milkweeeds were done blooming and the larger plants – common milkweed – were in seasonal decline. When the caterpillars arrived, they were munching on browning leaves which were beginning to fall, leaving them naked stems and the rough seed pods, instead of tender leaves, to eat. On some plants, cut back in July to encourage new leaf growth, that was favored. But their food factories generally had shut down, no longer producing enough of it for the caterpillars’ need.

Through earlier plant growth under climate change, a mismatch between feeding and food availability is playing havoc with migratory species the world over, potentially affecting the survival of many of them. Keeping more native plants in our gardens – food for people and butterflies and other wildlife – will help but not be effective, ultimately, without preventive action to also address this causal issue.