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January 1998
Looking out my window at the wintry landscape one grey afternoon, I conjured up an image of summertime in my yard. In my imagination, I meandered around, and found myself at the large stand of old-fashioned phlox, its dark pink flowers set off against the green of the leaves. I pictured the very large black and yellow garden spider that had taken up residence on a web spun among the tall stems. On late summer evenings I used to stroll out to visit it. Coming back to the present and the frozen view outdoors, I wondered, “Where is that spider now?”
“Definitely dead,” was the answer I got from Dr. Jim Dill, Extension’s Pest Management Specialist. The female of this spider species lays an egg mass enveloped in a brown silken sac about an inch wide. She secures it in the web close to her resting position near the center, and then she dies. In the fall, the eggs hatch and the spiderlings overwinter in the sac. From that sac this spring will come my complement of black and yellow garden spiders. They will grow during the summer and become large and, to me, decorative additions to my garden. The black and yellow colouring is effective camouflage in the late summer’s brown and gold grasses and shadowy light.
All spiders are predators, and most are opportunistic, locating themselves in places where they will likely find insect prey. The black and yellow garden spider lives in tall plants and shrubs in gardens and meadows where it is sunny and there is little wind. They sometimes build webs near flowers where insects come to collect nectar, such as my phlox stand. They also weave their webs on tall grasses, stretching them across trails where grasshoppers and other insects likely travel. Jim told me that when he was a boy running along the meadow trails on his grandfather’s farm, he often found a black and yellow spider on his chest, being himself too big prey to be snagged in the spider’s web.
The black and yellow garden spiders are orb weavers, an orb being an oval web. There are also spiders that weave funnel webs, usually on the ground. We notice them when they are all dewy on a summer’s morning. Then there are the free-hunting spiders that use no webs at all. One of these is a crab spider, sometimes called a flower or goldenrod spider. I saw one on my yellow yarrow, so it had taken on its yellow colouration as camouflage, although it is usually yellowish to white with pinkish streaks. The different types of webs, or no web at all, are variations in predatory styles. These are adaptations that, along with choosing different kinds of locations, reduce competition for prey and allow survival of many species. Depending on the species, spiders overwinter as eggs, immature spiders, or adult spiders. They are found under bark, in the soil, or in egg sacs on plants, like the black and yellow garden spider
If spiders have such varied life cycles, insects are equally elegant in their adaptations. I know that ladybug beetles overwinter as adults in my hallway. I don’t mind these guests, because they do no harm and eat aphids on my shrubs during the summer. “Lady” beetles got their name in the Middle Ages, when they consumed the insect pests on grapevines, and in gratitude were dedicated to “Our Lady.”
Like spiders, most insects live just one season or one year. For example, the adult fireflies we will see light up yards and meadows in early summer 1998, were eggs in late spring of 1997. They hatched in summer, becoming larvae, a worm-like stage in the process of metamorphosis, and fed on insect larvae, slugs and snails until fall. Then these firefly larvae hibernated and are now inactive. They are in rotting wood, under bark of dead trees, or in the soil. This spring, they will become active, and still in the larval form, begin eating again. In late spring, they will pupate, which is a resting stage, and in June, will be mature adults. Watch for the light show!
There are some exceptions to this one-year life cycle. Some species of the click beetle stay as larvae for up to seven years! They are active and feeding in warm weather, staying in the soil eating plant roots. We call the larvae wireworms. Finally, one spring, they become adults. Their name comes from the clicking noise made when one is on its back and springs into the air to right itself. The adult click beetle, as well as the adult firefly, does not eat.
Given that insects make up more than half of all the living things on earth, it seems a good thing that spiders, birds, mammals, and other insects include insects in their diet. Insects are an excellent source of protein. Many birds eat insects, focusing on what is most abundant at any particular time. They then supplement their diets with seeds or fruits when insects are less numerous. There are many species of birds that feed their young exclusively on insects, because the young need a high level of protein to develop. Another fortunate function of insects is pollination, which results in many of the fruits, vegetables, and seeds that we, and other animals, have come to enjoy.
If you are interested in insects and spiders, some references are helpful. The Golden Guides on insects, insect pests, spiders and butterflies and moths provide a good start for identification and learning. The National Audubon Society Field Guide to North American Insects & Spiders has colour pictures to aid identification and gives the natural history of each species. The Peterson Field Guide on Insects has drawings and information for identification. The University of Maine Cooperative Extension’s Pest Management Office and our county office provide identification and offer information on management alternatives, when needed, free of charge. We also have wonderful hands-on learning guides about insects and spiders for youth and adults.
By Nancy Coverstone (ncstone@umext.maine.edu), University of Maine Extension Educator in Androscoggin and Sagadahoc Counties
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