Several kinds of common insects in southeastern Pennsylvania are interesting, major parts of late summer and autumn. The following are only a few examples of them. These insects add beauty and intrigue in abundance to the local landscape. And they can be experienced and enjoyed by the most casual observers of nature.
Cabbage white and yellow sulphur butterflies swarm among the lovely pink blooms of red clover and the purple flowers of alfalfa in local hay fields to sip nectar in July through September. Some fields have so many of these butterflies from Europe fluttering among the blossoms at once that those fields seem to shimmer with butterflies. Though plain as individuals, these two kinds of butterflies are beautiful in their abundance.
Amorous males of various kinds of tree crickets and katydids begin chirping, trilling or chanting, depending on the species, by the end of July through to October to attract females of their respective species to them for mating. They make their music by rubbing their wings or legs together, again depending on the species. They start their chorusing at dusk and continue into the wee hours of the night, concerts that make the males more vulnerable to predation.
Snowy tree crickets are a common member of their family. Males of this species scrape out measured, monotonous chirps that tell us the temperature. Count the number of chirps in 15 seconds and add 40. That will fairly accurately record the temperature.
Male true katydids use files and scrapers on their wings to scratch out "Katy-did" seemingly without end. But there is an end to all the crickets' and katydids' serenading sometime in October when heavy frost kills all the adult crickets and katydids. Those species survive the winter only in the egg stage.
Annual cicada grubs emerge from the ground on August nights and climb trees and other objects. They had spent the previous year sucking sap from tree roots in the soil. But now they are ready to be adults, reproduce and die.
The exoskeleton of each grub up a tree splits down the back and the adult emerges from it. When that insect's wings are fully pumped out, it flies off in search of a mate. Male cicadas create a whining sound by vibrating plates on their abdomens. One can hear that trilling during the heat of the day and, especially, in the evening. Females hear that sound and come to the males to mate.
Grassy, weedy roadsides and some fields jump with a few kinds of common grasshoppers in summer. And by August and September those grasshoppers are large enough to see jumping and flying away from the observer, as they do to escape predators. All these grasshoppers eat grass and other plants. And all are brown or green to blend into their surroundings so they are not so easily seen by predators such as birds, foxes and others.
Carolina locusts are brown and good fliers. When they are in flight, one can see yellow and black or their wings.
Differential grasshoppers and red-legged grasshoppers are both "short-horned", which means they have short antennae. Red-legs do have a bit of red on their large, rear, jumping legs.
And there are a couple species of long-horned grasshoppers in this area, including gladiators and cone-heads, which are both mostly green. Gladiators seem to have a shield on their thoraxes and cone-heads have pointed heads, hence their common names.
Monarch butterflies are most prevalent here late in summer. We start seeing them in this area early in July. Females of the species at that time lay eggs individually on milkweed leaves, which the caterpillars consume. Adults sip nectar from a variety of flowers.
Eggs of the last generation of the year are laid on milkweed in early August. The resulting caterpillars pupate about the third week of August and emerge as butterflies early in September. But these monarchs do not breed. Instead, they migrate southwest across the United States to certain forests in mountains of Mexico where they spend the winter. But the miracle of their migration is they were never in those forests before. Yet every year, the last generation of each year finds the very woods in Mexico their great grandparents left early in March when they migrated north. How do they know where to go and when they arrived at their destination. Nobody knows. But it seems all monarchs that winter in those Mexican woods are related and originally came from a small population of monarchs in those patches of woods in Mexico.
In September and October when we feel autumn and the approach of winter, swarms of inseminated female box elder bugs gather in sunny places near cover in rock walls, tree cavities and crevices in buildings, among other sheltered spots. They are true bugs, in the bug family of insects, that are attractive with red and black color patterns. Eventually, those masses of bugs will enter various shelters to spend the winter in relative safety.
Box elder bugs spend summers sipping sap from twigs on box elder or ash-leafed maple trees that grow on flood plains along waterways. But with the approach of winter, they seek sheltered places to spend the winter and that's when we see them in large swarms. They are harmless to us, however. They do not bite or sting and they don't eat anything through winter.
In October, we see thousands of handsome woolly caterpillars crossing country roads, as each one is seeking a place in the soil to spend the winter. These caterpillars are bristly with stiff hairs to ward off predators. They have black hairs at both ends and reddish-brown ones in the middle.
Woolly caterpillars ate grass and other plants in summer. They pupate in the ground through winter and emerge the next year as Isabella moths. Those moths lay eggs in the soil, then die. The young that hatch from those eggs will be another generation of attractive woolly caterpillars. Keep your eyes and ears open to experience some of these common and interesting species of insects in southeastern Pennsylvania. They are entertaining and inspiring.
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