Wildlife: The secret lives of spittlebugs, gall flies

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Insects thrive during summer, and many are conspicuous and familiar. Flies and ants plague outdoor activities, hornets terrorize us and fireflies and butterflies delight us. Many insects, however, 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 old field vegetation. Upon emerging, the tiny nymphs inserted their piercing, sucking mouthparts into the plant tissue and began ingesting plant fluids.

Over the course of five weeks, the spittlebug nymphs grew slowly and excreted copious amounts of liquid waste and air 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 1/4 inch), drably colored and sometimes called froghoppers because large eyes on the sides of their heads give them a frog-like appearance.

Evidence of gall insects is also easy to find, but the actual adult insects are elusive. 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.

I often find goldenrod gall flies in old fields in late summer. 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. The goldenrod responded by forming a small swelling around the maggot. It is this tissue that we call the gall.

Over the next three weeks the gall grew to the size of a ping-pong ball. In October as temperatures drop, the maggot goes dormant. At this time you can bisect galls with a sharp knife to find the resting maggot. Downy woodpeckers know this trick, too, and often cling to goldenrod stems while hammering the gall to extract the nutritious maggot.

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

Biologist, author and broadcaster Scott Shalaway can be heard 8-10 a.m. Saturdays on 1370 WVLY-AM (Wheeling) and online at www.wvly.net. He can be reached at www.drshalaway.com, sshalaway@aol.com and 2222 Fish Ridge Road, Cameron, W.Va., 26033.

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