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Trees, Caterpillars and Butterflies in the Backyard

Red Admiral Butterfly

Red Admiral butterfly

I have trees, caterpillars and butterflies and other pollinators in my backyard. Trees provide us with many environmental services. The obvious benefit is cooling shade. When we visited friends in Sacremento we learned that the Sacremento Municipal Utility District (SMUD) was putting trees on residential properties to cool the houses and lower the cost of power. Other benefits are not so obvious. They filter our air, take in carbon and breathe out oxygen. They filter water to protect our streams and rivers and prevent erosion. These are essential services.

Trees also make our gardens beautiful in multiple ways, beginning with the shape and texture of foliage. They can provide colorful flowers in the spring. Think of the loveliness of redbuds, magnolias, serviceberry, dogwoods, as well as blooming fruit trees that will give us a harvest. We can see and enjoy that beauty. What we cannot see is the ways trees help keep all the nearly invisible creatures in the garden in balance.

spicebush butterfly caterpillar

Spicebush butterfly caterpillar photo by Bill Benner

Many of us don’t give too much thought to pollinators, especially since many of them are so tiny that we don’t even see them, but we do think about how nice it is to have beautiful birds and butterflies in our gardens. Many of us put out bird feeders to attract birds, and aside from suet with seed blocks, most feeders hold seeds. However, especially in the spring birds need bugs and caterpillars to feed their young.

While many birds do have a diet that depends on seeds almost all North American birds depend on insects to feed their babies because of their great need for protein. Insects provide that protein and other nutrients in good measure. I also just learned that if there is any chance bluebirds might nest in or near your garden a makeshift feeder for mealworms would be very attractive. Bluebirds eat many other insects and mealworms should not be used as the sole bluebird food, but a helping every morning would keep the baby bluebirds thriving.

In his book Bringing Nature Home: How Native Plants Sustain Wildlife in our Gardens, Douglas Tallamy describes and explains how important insects are for birds. He also explains why using pesticides in the garden in order to keep flowers and foliage looking pristine is a bad idea.

Monarch caterpillar

Monarch caterpillar

Native trees like red maple, sugar maple, river birch, white oak, red oak and black oak, to name just a few, are all strong enough to let insects eat their fill without damaging the vitality of the tree. He says that oaks, willows and cherries combined are trees that support about 1400 insect species, including butterfly larvae, otherwise known as caterpillars. Butterfly caterpillars often have very specific plants they can feed on in order to live through their cycle of egg, larvae, pupa otherwise known as chrysalis, and finally adult butterfly. Most of us know that the endangered monarch butterfly depends on the different species of milkweed plants as hosts where they can lay their eggs, so the larvae will have the proper food when the eggs hatch.

When we lived in Heath we did have a pussy willow. One day when I was examining it to see how much damage a browsing moose had done I saw an odd brown bump on a stem and leaf. What was it? Some kind of disease growth on the willow or something else? A little research and I found that it was the larval form of the viceroy butterfly. The viceroy larvae masquerades as a pile of bird poop, which no bird would ever think looked appetizing.

Swallowtail butterfly

Swallowtail butterfly

Here is a very short list of common trees that act as host plants for particular butterflies:

Viceroy                                   Willow, aspen, cherry, plum, poplar

Mourning cloak                       Elm, poplar, willow

Red spotted purple                 Apple, aspen, hornbeam, poplar, willow, cherry

Giant swallowtail                    Hop tree

Question mark                         Hop tree, elm, hackberry

Spring azure                            Dogwoods

Baltimore checkerspot            White ash

Hairstreaks                              Oak

Elfins                                       Pines

Dr. Bob Benner, veterinarian extraordinaire, gave a talk to the Greenfield Garden Club at their annual meeting recently, about butterflies, their needs, and the delight they can bring to our gardens and to our eyes. His photos of some of the 105 Massachusetts butterfly species, including their caterpillar stage, were stunning, and surprising. He gave us advice about choosing plants to act as hosts and provide nectar. He also gave us permission to be a little casual about weeding because some ‘weeds’ act as host plants for caterpillars.

He also suggested that we might want to join the Massachusetts Butterfly Club which has numerous benefits including about 50 butterfly field trips a year, publications like the twice yearly journal Massachusetts Butterflies and the MBC Guide to Good Butterfly Sites which comes with maps.

Benner left us on tenterhooks as he told us about the election to choose a State Butterfly. The MBC partnered with Girl Scout Troop #85103 of Norfolk and proposed the Black Swallowtail, the Mourning Cloak or the Great Spangled Fritillary. Voting ended this past October and now we wait for the results. Benner suggested that we might be looking to the Black Swallowtail to win. Can’t wait for the announcement.

Between the Rows   February 10, 2018


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