SSAT Practice Test 5

¹On a summer night, a single streetlight can draw moths from a surprising distance. Many of them never leave. They circle the lamp until they are exhausted, drop to the pavement, or are picked off by bats and spiders that have learned where easy meals gather. Multiply that lamp by the millions that line the world's roads, and it becomes hard to dismiss artificial light as a harmless convenience.

²Insects matter more than their size suggests. Moths pollinate many flowering plants, often at night when bees are inactive, and their caterpillars are a staple food for nesting songbirds. Researchers who have reported steep declines in insect numbers in some regions point to several causes, including habitat loss and pesticides. Light at night is rarely the leading suspect, but it is one of the few causes a town could reduce quickly, and at low cost.

³The changes are not complicated. Studies have found that many insects are drawn most strongly to light at the blue end of the spectrum, the kind produced in abundance by the bright white LEDs that many cities have installed to save energy. Warmer, amber-toned lamps attract fewer of them. Fixtures shielded so that light falls downward, rather than spilling sideways and into the sky, shrink the area from which insects are pulled in. And lamps that dim or switch off in the late hours, when streets are nearly empty, give nocturnal animals back part of the night.

⁴Critics sometimes argue that such measures sacrifice safety for the sake of bugs. But a shielded lamp puts more of its light on the sidewalk, where people actually need it, and less into the eyes of drivers and the windows of sleeping residents. The goal is not darkness; it is light that goes where it is useful.

⁵Few conservation measures ask so little. A town cannot restore a lost meadow overnight, but it can change a bulb.