Saugus Gardens in the Summer

Here’s what’s blooming in town this week to make your walks more enjoyable

By Laura Eisener

This past weekend I was delighted to see the first monarch butterflies to visit my garden this summer. Their arrival often coincides with the first blossoms on the butterfly bush (Buddleia davidii), which is one of their favorite nectar sources. This fragrant shrub, sometimes called summer lilac because of its fragrance although it is not closely related to lilac, attracts a wide range of other pollinators as well.

According to the U.S. Fish and Wildlife Service, Monarch butterflies (Danaus plexippus) fall into two distinct populations: the range of eastern monarchs is between Canada and Mexico, travelling through most states east of the Rocky Mountains, while the western population stays west of the Rockies and goes from Canada to California and the southern United States, with many overwintering in southern California. There are some in Florida which don’t seem to migrate nearly as far, if at all, as others in their species. The longest migrations, about 3,000 miles, may take more than one generation. Western populations seem to be in more severe decline than eastern ones, and habitat loss may be one of the reasons.

Gardeners can help monarchs in general by planting more of their host plants, which are several non-tropical species of milkweeds, including butterfly weed (Asclepias tuberosa), swamp milkweed (Asclepias incarnata) and common milkweed (Asclepias syriaca). Just a few human generations ago, common milkweed was generally considered a weed to be eliminated in a well-cared for garden. Gradually people began to appreciate this plant’s importance for the monarch’s reproduction, and more people are planting this native plant with its spherical umbels of fragrant pinkish purple flowers instead of removing it from their gardens.

All members of the milkweed genus have sticky white sap that is toxic to many pests and predators so helps protect the plant. This toxicity is passed on to the monarch butterfly’s larvae, who are not harmed by it, but in turn it protects them from predators who might prey on them. Both the larvae and the adult butterfly are often avoided by insects and birds that regularly eat other butterflies. In turn, some look-alike orange butterflies may benefit from their similarity or mimicry of the monarch’s appearance. The viceroy butterfly (Limenitis archippus) is not toxic, but many predators may avoid it because of its similarity to the monarch butterfly. The milkweed plants, their sap and the butterflies are not toxic to the touch, but only if eaten. The sap can present challenges for anyone wanting to use the milkweed flowers in bouquets, as the sticky sap can prevent other flowers in the arrangement from taking up water

In addition to the select species that the monarch butterflies can lay eggs on, they need nectar from a variety of flowers along their migration. Adult butterflies eat nectar from a wide range of flowers, native and introduced, and occasionally also pollen and even fermented fruits. They can also eat the nectar from the milkweeds, but they need other flowers during the spring and fall outside the milkweed blooming period. Joe Pye weed (Eutrochium spp.), New England asters (Symphiotrichum novae-angliae) and several goldenrods (Solidago spp.) help give the butterflies energy for their fall migration.