Don’t be alarmed, but the Arboretum is crawling with insects. Then again, so is nearly every inch of land on the planet. There are about a million named insect species and likely several million more yet to be identified. It’s estimated that known insect species make up close to 70 percent of all known animal species on earth.
Insects and plants are intrinsically linked and have evolved some often fascinating relationships. For plants, these interactions can be negative, as when insects eat foliage or their larvae tunnel through a tree’s cambium. The most devastating negative insect impacts on plants often occur when non-native insect species are introduced to native plant populations. Many plants have defense mechanisms (e.g., toxic compounds in leaves) that limit or prevent damage from herbivorous (plant-eating) insects with which they have coevolved in the same region, but those defenses may be ineffective on an insect species from a region far removed. Arnoldia has featured articles on a number of troubling introduced pests including wood borers and bark beetles [pdf] (and specifically the effect Asian long-horned beetle [pdf] has had in Massachusetts), hemlock woolly adelgid [pdf] (more here [pdf]), and gypsy moth [pdf].Of course there are also many positive (and essential) plant-insect interactions, especially when it comes to pollination. Some entomophilous (insect pollinated) plant species have evolved unique relationships with insect species that have features ideal for pollinating that plant. Bees, especially honey bees and bumblebees (which have an amazing way of pollinating flowers [pdf]), are well known for their pollinating prowess; many economically important fruit and vegetable crops depend on bee pollination for fruit production. Plants in the Arboretum’s collections may be pollinated [pdf] by bees, flies, beetles or other insects (read the fascinating story of insect-aided magnolia pollination here [pdf]), so when you visit this spring be sure to appreciate not just the beauty of the blossoms but also the amazing insects hanging out around those flowers.