Garden Bugs: Nifty or Nasty?

Like most of life, my garden is a mix of good and not so great: desirable plants and weeds, loamy soil and heavy clay, beneficial insects and annoying pests — and early August brought many types of insects to our garden. Here are just a few stand-outs.

Japanese beetles (Popillia japonica), an invasive species, are a type of scarab beetle that destroy many plant species in North America.

The biggest pest in our yard is the Japanese beetle, which skeletonizes the flowers and leaves of many plants. A few weeks ago they favored apple and crabapple trees, but I’ve also pulled them off of my rose, asters, day lilies and purple coneflowers. Now, they are shredding my hosta and anise hyssop blossoms. According to the Minnesota Department of Natural Resources, the beetles are native to northern Japan and probably arrived in a shipment of iris bulbs in 1916. They have no natural predators, although some birds, such as starlings, robins, bluejays and sparrows will sometimes eat the adult beetles and the grubs, which live in lawns.

Yesterday I picked 46 beetles off of my royal standard hostas. I used to squish them, but that releases their pheromones, which attract more beetles. Now I pick them off by hand and drop them in a small pail of soapy water, which kills them quickly without releasing their pheromones. I don’t use an insecticide because so many beneficial insects would die from the chemicals.

The convergent lady beetle (Hippodamia convergens) is a North American native that feeds on aphids, whiteflies and other pests.

Not all ladybugs are red or orange. The tiny esteemed ladybug (Hyperaspis proba) is black with yellow spots.

Unlike the Japanese beetle, ladybugs, or ladybird beetles, especially those native to North America, are beneficial to gardens. More than 500 species of ladybugs have been identified in the United States. Mom taught us never to harm ladybugs because they eat aphids, a major garden pest. Our native ladybugs don’t bite, so if you feel a pinch and find it’s from a ladybug, it is likely to be an Asian ladybug, which do nip — mainly because they seek moisture and salt, or they feel threatened. Asian ladybugs were imported in the 1970s to help destroy predators in agricultural operations. I let them be when I find them because they destroy so many aphids and other pests. However, the native ladybugs are better suited to our gardens and plant species.

Aphids, that favorite food of ladybugs, are tiny, often wingless, and very plentiful. There are more than 300 species of aphids in Minnesota and they are found on all types of plants. Most aphids on a plant are females that reproduce asexually, without having to mate. They also give birth instead of laying eggs. The newborns are clones of their mother, so they, too, are female. (Environmental conditions sometimes cause females to produce both female and male offspring, which are genetically identical to the mother, except that males lack one sex chromosome.) They come in many different colors. I’ve seen green, black, red, and I have orange ones on some of my milkweed plants. When aphids suck a plant’s sap, it causes curling, yellowing and browning of the leaves. Aphids also secrete a sticky, sweet liquid called honeydew. Last summer, during a heavy infestation of aphids, my milkweed plants were dripping with honeydew and covered with ants, which are attracted to the sweet liquid. Even though I washed the milkweed with water from the garden hose daily, the plants were disfigured and messy.

Tiny soft-bodied aphids (Aphids nerii) suck plant juices from common milkweed. The white specks are moltings that are stuck in the honeydew.

 

This juvenile male eastern pondhawk (Erythemis simplicicollis) will attack any type of insect its own size or smaller, including others of the same species.

In contrast to the slow, rather clumsy flight of beetles, several species of dragonfly dart and swoop among the garden plants. Perched on a milkweed leaf, a green eastern pondhawk zips lightning-quick from its perch to capture a fly. Its powerful jaws quickly crush and consume its prey. Common in gardens, dragonflies eat mosquitoes, gnats, flies and other insects. Their shining colors add beauty to the garden.

Most meadowhawks (Sympetrum spp.) fly in late summer and autumn.

Monarchs, red admirals and other butterflies are frequent visitors to our garden — especially now when the milkweed is blooming and the plants are in their prime for feeding monarch larvae. These tiny caterpillars feed only on milkweed and I discovered two of them a week ago. Adult monarchs sail through the garden stopping to nectar on milkweed, Joe-Pye, garden phlox and purple coneflowers.

Monarch caterpillars hatch and grow only on milkweed plants.

Adult monarchs (Danaus plexippus) and many other butterfly species nectar on common milkweed (Asclepias syriaca).

A red admiral (Vanessa atalanta) nectars on garden phlox (Phlox paniculata).

Red admirals are smaller and fly faster and more erratically than monarchs. A male finds a sunny spot and watches for a female to fly by. After mating, the female lays eggs on nettle plants. Adults nectar on milkweed, red clover, ripe fruit and tree sap. They are one of the few species that overwinter in Minnesota, often in a wood pile or mound of leaves.

The summer garden harbors so many interesting, and often beautiful, insects. Next time you’re working in your garden, or simply enjoying your yard, take a look at the diversity of these tiny creatures all around us. The majority of them are either beneficial or harmless. Nifty or nasty? You decide!

4 thoughts on “Garden Bugs: Nifty or Nasty?

  1. Japanese beetles . . . UGH! I do the same thing to get rid of ours, but the only place they have attacked this year is our raspberry and rose bushes. I have picked off thousands, (every day I remove several hundred from our raspberry bush patch). However, I love all the other insects you posted. One plus of removing the Japanese beetles is how much fun it is to watch the bumblebees and other tiny creatures at work.
    Thanks so much for your posts!

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