Arizona Highways Online
Convergent Ladybug Beetle - Hippodamia convergens
By Kathryn Eastlick
Gardeners and farmers depend on them, and children squeal with glee when one lands nearby, but the convergent ladybug beetle strikes mortal terror into the heart of one creature the aphid. To us, the ladybug is a roly-poly, polka-dotted, happy little bug, born to help crops thrive and give children pleasure. But to aphids, the hard-shelled beetle spells doom.
Convergent ladybugs (so named for the white dashes on their thorax) have an insatiable appetite for aphids, which is lucky for us, because if they didnt voraciously nosh on the tiny plant-eating insects, the aphid army could destroy an entire yard within a month. One ladybug can eat about 600 aphids in its lifetime. That may not seem like very much, but keep in mind the average ladybug is smaller than the tip of your pinky finger.
Convergent ladybugs have short legs, a small, downturned head, and six black spots on each orange wing. Although seemingly small and vulnerable, ladybugs have few predators. Would-be attackers like birds need only sample the foul-tasting beetle once to know never to chomp into a ladybug again. When they do feel threatened, ladybugs will play dead or secrete a stinky yellowish fluid from joints in their legs.
The life of a ladybug begins in spring when an adult ladybug lays her eggs underneath a leaf. The eggs hatch in less than one week, and the emerging larvae are far-removed from the cute orange bugs so admired by all. Ladybug larvae are monstrous looking creatures, black and dragonlike with warts and orange markings. The larvae do not have wings but are very mobile, gorging themselves on aphids and then entering the pupae stage. After they emerge as adults, the ladybugs soon realize that the aphid population has dwindled dramatically, and decide to take off for a summer vacation in the mountains.
Convergent ladybugs descend in droves on Arizona mountaintops every year, turning trees, rocks and shrubs into quivering orange chimeras. Entomologists say that in midsummer, the population can reach concentrations of 120 million ladybugs per acre. The mystery of this massive migration is that no one knows for sure why the ladybugs retreat to the mountains since the peaks do not offer a bountiful aphid population. Entomologists speculate that the ladybugs enjoy the humidity and temperature, or they may be drawn to the mountains by odors left from last years ladybugs.
Once encamped on the peaks, the ladybugs resort to feeding on pollen, which stimulates sleep-inducing hormones. As a result, they enter a dormant period in which they snooze for long periods, awakened only by rain or unexpected temperature changes. When they do wake up, they fly about groggily and perhaps get a bite to eat. In November, the ladybugs huddle together, tuck their heads under the belly of their neighbor to stay warm, and begin their winter hibernation.
When the first winter thaw occurs, the beetles will wake up and mate (the voluminous congregation makes it easy for even the pickiest female to find a suitable mate). Afterward, the ladybugs experience a collective craving for aphids, so they fly back down to their places of birth. Once there, they enjoy a feast of aphids, which in turn stimulates the female reproductive system. The female lays her eggs and promptly dies. Within one week, the eggs hatch, the aphids tremble, and the ladybug cycle begins again.
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