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Bugs and Birds—

The earliest of the swallow clan to turn up in Maine each spring, Tree Swallows depend heavily on flying insects for survival during those still-chilly days. On March 31, I stood at Warren’s river shoreline, marveling at their swift darting maneuvers. The afternoon temperatures had climbed into the low 50s as the energetic swarm of 20 hungry swallows darted after hatches of insects above the river. One slender, long-legged insect from the hatches clung against my cheek, apparently some form of emergent mayfly.

Another early migrant, an Eastern Phoebe, announced itself from nearby, giving its gritty “phoebe!” calls. The gray-and-white flycatcher bounced its tail emphatically as it alternated between perches in search of food. By mid-to-late May, eight other flycatcher species will appear across Maine in timing with the seasonal insect booms.

Spring warbler migration is now under way, a continuum of northward travel that spans the next month or so. Since warbler diets consist exclusively of insects, only a few hardy species can arrive and thrive in April. Their initial feeding sites are often found at the margins of wooded lakes and streams. These include Palm Warblers, Pine Warblers, flashy Yellow-rumpeds and Black-and-White Warblers. The bi-colored Black-and-White Warbler’s foraging habits are concentrated mainly on bark crevices of large limbs and tree trunks. Reminiscent of nuthatch behavior, this warbler’s distinctive feeding style may be advantageous while cooler weather conditions limit the quantities of free-flying insects.

And the broad scope of insect-seeking songbirds extends throughout the jays, cuckoos and blackbirds to other species we might not consider as insect eaters, such as gulls and raptors. In summer you may have noticed occasional groups of gulls in weaving, erratic flight patterns as they pursue insect hatches hundreds of feet overhead. Raptors as insect consumers? American kestrels and merlins frequently supplement their diets with dragonflies, butterflies and other large insects throughout the summer.

Insects represent the largest class of animals on earth and comprise more than half of known living organisms. They serve as the base of the food web for a host of creatures in the natural world. For humans, insects are generally viewed as annoying pests, like that insistent mosquito that buzzes into your ear canal during an evening cookout. And increasing numbers of ticks certainly promote Lyme disease. For the most part, we have sought to control major insect populations through broad-scale chemical applications at agricultural sites and residential areas.

A mounting question is this: Have we succeeded too well in some aspects of our control efforts? Some scientific studies suggest that 40 percent of all insect species are in decline and could die out in the coming decades. We might be tempted to shout hip, hip, hooray! But, to use an old expression, there could be a fly in this ointment. It appears that insecticides have also affected non-targeted insect species, and neonicotinoids have been implicated in the worldwide decline of vital pollinators such as bees. About three-fourths of all flowering plants are pollinated by insects, as well as crops that produce 75 percent of the world’s food supply. Without pollinators, our current diets would be severely limited and overall nutritional values of vitamins and minerals would be reduced. In some parts of the world, crops are now being hand pollinated because pollinating insects are missing from those environments. Apple and pear crops in Szechuan, China, and some Brazilian crops are current examples. Hand pollination is a costly enterprise that was formerly performed by colonies of bees for free.