Exploring The Mystery Of Summit Ladybugs

Wait… Did Someone Mention Summit Ladybugs?

Have you ever been on a mountain and seen hundreds, possibly thousands, of ladybugs crowding on a rock or log? Have you ever seen photos showing the occurrence? Have you ever noticed the occurrence does not happen all year? Have you ever wondered what causes the phenomenon? If you answered “yes” to any of those questions, then this article might be suited for you.

Who Cares About Ladybugs?

Technically, and contrary to popular belief (at least in North America) ladybugs are not true bugs at all. They are beetles. Many scientists prefer referencing the names ladybird beetle or lady beetle as identifying names, rather than the more widespread and less accurate ladybug moniker. However, for the purposes of this article, the more common and recognizable (at least in North America) ladybug name will be referenced.

The name of the beetle is rumored to have been derived in Europe during the Middle Ages. European folklore states there was once a plague of insects devouring agricultural crops. After Catholic farmers prayed to the Virgin Mary for assistance with getting rid of the menacing insects, legend claims that beetles came from the sky and began eating all of the crop-damaging insects. The farmers, believing their prayers were answered by the Virgin Mary herself, nicknamed the saviors “Beetles of Our Lady,” which later got shortened down to ladybugs.

But do not be fooled by the name. Ladybugs are certainly not damsels, let along damsels in distress. The beetles have been around for many millennia, with the earliest identifiable fossils of ladybug ancestors dating back to the Cretaceous Period (between 144 to 65 million years ago). Ladybugs are found throughout the world, on every continent but Antarctica. In fact, there are over 5000 species of ladybugs, approximately 450 of which are native to North America.

Of those many ladybug species in North America, only one of those species is a regular peakbagger:
Hippodamia convergens, the convergent ladybug.

Time To Eat!

Ladybug, ladybug fly away home,
Your house is on fire and your children are gone,
All except one,
And her name is Ann,
And she hid under the baking pan.
-Old English Nursery Rhyme

For only a several months during every year, typically during Spring months, the convergent ladybug becomes a voracious eater of aphids. Although the convergent ladybug can survive for long periods on other substances such as pollens, nectars, flower petals, and soft plants, aphids are an integral food source for the life cycle of the convergent ladybug. Without aphids as their primary food source, female convergent ladybugs reabsorb their eggs within their bodies rather than laying them. With aphids as their primary food source, female convergent ladybugs can each lay 200-1000 eggs during one Spring season. Adult convergent ladybugs prefer feeding in areas of large aphid populations, to increase egg laying potential. In such areas of large aphid populations, it is not unusual for an adult convergent ladybug to consume an average of 22 aphids per day.

Ladybug larvae hatch within 3-6 days after eggs are laid. Like adults, larval and pupal convergent ladybugs require consumption of aphids to ensure survival. This is yet another reason that adult convergent ladybugs seek areas of large aphid populations; it ensures the survival of the species. Not all adults reproduce during aphid-feeding periods; some will wait until the following Spring to do so. As the aphid-feeding season ends, the species begins migrating towards potential hibernation locations.

The convergent ladybug is the most common species of ladybug in North America, and as such has many places to choose for hibernation locations. As the aphid-feeding season ends towards late Spring, many convergent ladybugs remain in those areas and find hiding places such as under leaf litter or under logs for which to begin hibernation. Many others will migrate away from the feeding areas to find similar low elevation locations for which to begin hibernation.

Still some others, especially in the western half of the North American continent, will migrate far away from the feeding areas to mountainous areas…

Head For The Hills!

During late Spring and early Summer, many convergent ladybugs begin migrating towards mountainous areas. The trek is not a graceful, straightforward type, as wind currents and air temperatures greatly influence migratory patterns. Winds help propel the flights of convergent ladybugs, pushing them higher and closer towards higher elevations. However, once the ladybugs reach air temperatures of approximately 55°F they need to stop flying, triggering a temporary free-fall until their bodies can warm up enough to continue the migration. This causes a sort of repetitive oscillation effect, the side-view of which would look like a sine wave.

Mountain-bound convergent ladybugs are not typically in swarms during these in-flight migrations. Occasionally, they will land on ground to consume pollens and nectars as a means to fatten up their bodies for survival during hibernation. However, once they find their desired high elevation summits they tend to swarm en masse and form colonies. Most of these mountain summit goals range between 6000’-8000’ elevation, but some might be as high as 10000’ elevation (or possibly higher) depending on current conditions.

It is during these periods of summit swarms that mountaineers most frequently notice the ladybugs. Where there is one ladybug there is usually hundreds if not thousands congregrating nearby. Many ladybug dealers/collectors claim that some of these mountain colonies can contain as many as 500 gallons of ladybugs, with each gallon containing up to 72,000-80,000 ladybugs. The beetles remain on their high elevation homes throughout the Summer months. This timeframe represents the beginning of diapause, which is the nine-month period of hibernation process for convergent ladybugs. Many within the species will begin mating during this first stage of diapause, and larger colonies have greater chances for successful mating.

It is unknown exactly why many convergent ladybugs seek out high elevations, but many people speculate it is because high mountain summits are located far away from most primary predators such as other insects, birds, and spiders. It is also unknown why certain summits are preferable ladybug gathering sites over other nearby summits, but many people speculate it might have to do with the coloration of the summit terrain, surface temperature of that terrain, and/or hiding places (such as cracks) within that terrain.

Time Flies (And So Does A Ladybug)

Those interested in seeing this unique high elevation phenomenom should do so while the opportunity presents itself. During late Summer and early Autumn, as the weather becomes rainier and temperatures cool, many of the convergent ladybugs leave the high mountain summits in favor of lower elevations. In many instances, they migrate to sub-alpine areas within 2000’-5000’ elevation, only to hide under leaf litter, in or under logs, or other secluded locations for which to spend the remainder of their diapause in a dormant to semi-dormant state.

These locations later become covered for many months by Winter snowpack, insulating them from the harsh sub-freezing winds and temperatures that would otherwise kill them. Some days might occasionally be warmer than normal, and during those periods some mating will occur as the beetles temporarily become active again. Later, after temperatures become warmer during late Winter and early Spring, the ladybugs begin to emerge and migrate back to their Spring aphid-feeding and reproducing areas, restarting the cycle.

North America is not the only continent which experiences summit ladybugs. Several relatives of the convergent ladybug create similar phenomena on other continents.


So the next time you find colonies of ladybugs converging on on a summit, just remember it is a natural occurrence that should be treasured and enjoyed while it lasts.

Bibliography

Grossett, Sara Elizabeth. "Migratory Patterns and Diapause of Hippodamia convergens (Convergent Ladybug)." Apr. 2011. 17 Jun. 2011

Lyon, William F. "Lady Beetle: HYG-2002-98." Ohio State University Extension, Horticulture and Crop Science. Accessed 21 Jun. 2011

Signer, Ian. "The Biogeography of the Convergent Ladybird Beetle (Hippodamia convergens)." San Francisco State University, Department of Geography. Fall 1999. 17 Jun. 2011

Wineke, Andrew. "Ladybugs are Heading for Colorado Hills." Colorado Springs Gazette. 26 Aug. 2009. 20 Jun. 2011
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Primary Image:
Convergent ladybugs atop Centennial Cone (Colorado), photo courtesy of "sarah.simon"

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