Insects: Spittlebugs, galls, and evening singers

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Insects thrive during the warmth of summer, and many are conspicuous and familiar. Myriad species of flies and ants plague our outdoor activities, hornets terrorize us, and fireflies and butterflies delight us. Many insects, however, are less conspicuous and seldom recognized. Some are rarely seen as adults.

For example, back in the spring as daily temperatures warmed, tiny eggs of meadow spittlebugs hatched on the stems of grasses and other vegetation in fields and meadows. Upon emerging, the tiny nymphs inserted their piercing-sucking mouthparts into the plant tissue and began ingesting the plant fluids.

Over the course of five weeks and five larval instars, the spittlebug nymph grows slowly and excretes copious amounts of liquid waste, air, and glandular secretions to form a frothy spittle-like mass. The spittle prevents the nymphs from drying out and hides them from potential predators.

Adult spittlebugs are small (about a quarter-inch), drably colored, and sometimes called froghoppers because large eyes on the sides of their heads give them a frog-like appearance. So next time you find a white spit-like mass on herbaceous vegetation, you’ll be gazing on the foraging stage of the meadow spittlebug.

Evidence of gall insects is also easy to find, but again the actual adult insects are rarely seen. A variety of insects including some flies, wasps, and moths cause plants to form unusual growths called galls. A gall is a plant’s response to attack.

Galls formed by goldenrod gall flies in old fields in late summer are easy to find. Gall formation began back in the spring when females sought out young goldenrod stems and deposited an egg in the terminal bud. After hatching, the tiny maggot tunneled down the stem beneath the area of active growth. There the goldenrod responded by forming a small swelling around the maggot. It is this tissue that becomes the gall.

Over the next three weeks the gall grows to almost the size of a ping pong ball. In October as temperatures drop, the maggot goes dormant. At this time you can bisect the gall with a sharp knife to see the resting larvae. Downy woodpeckers know this trick, too, and often cling to goldenrod stem while hammering the gall to extract the tasty maggot.

After a long winter sleep, the maggots chew a tunnel out to the very edge of the gall and then return to the central chamber to pupate and transform into an adult fly. After a few weeks, the fly escapes through the previously excavated escape tunnel, and the life cycle begins anew.

A final example of a common, but seldom seen insect is the snowy tree cricket. They sing a seemingly endless series of high-pitched melodic chirps that to many almost define a warm August night.

Though often heard and recognized, snowy tree crickets are almost impossible to find.

During the day they feed and rest amidst the foliage of trees and shrubs. Thanks to their small size and cryptic pale green color, they blend in seamlessly with their surroundings. And at night, their song has a ventriloquistic effect. Shine a light where you think the tree cricket must be and sure enough it’s not. It takes good eyes, patient scanning, and a little luck to find a singing tree cricket.

Like more familiar katydids, which have also begun singing about a week ago, snowy tree crickets produce the sounds we hear via a process called stridulation. They rub one body part against another. To “sing,” they elevate their front wings and move them back and forth. Where the wings overlap, a sharp edge (the scraper) on one wing rubs against a file-like ridge (the file) on the other. Membranes on the wing act as a sounding board to amplify the sound. The process is not unlike the sound that resonates from the body of a violin when the bow is pulled across the strings.

For the next month or so, the evening choruses produced by these nocturnal grasshoppers, which can at times be deafening, are a reliable sign that summer is beginning to wind down.

About the Author

Scott Shalaway, who holds a Ph.D. in wildlife ecology from Michigan State University, writes from his home in rural West Virginia. A former faculty member at Oklahoma State University and the University of Oklahoma Biological Station, he has been writing a weekly nature column for newspapers and freelancing for magazines since 1986. Send questions and comments to scottshalaway@gmail.com. You can also visit his Web site, http://scottshalaway.googlepages.com. More Stories by Scott Shalaway

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