All life forms have strategies for getting through the cold winter months, and ladybirds are no different. They’ve developed 3 different methods to stay warm and avoid being eaten by predators. While some species may just hunker down, others will simply fly away and avoid the cold altogether. Below, we’ll give you an overview of the methods they use to make it through winter.
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1. Hibernation
Most ladybirds, also known as ladybugs and lady beetles, can live for several years. To survive the cold winters we experience throughout most of North America, they must go into a special type of hibernation called diapause.
While diapause is a form of hibernation insects use, it doesn’t involve sleeping. It is usually triggered by an environmental cue, such as cold weather, which causes the insect to stop their physiological processes until conditions become favorable again. To put it simply, they shut down their system for the winter to survive the cold.
By Alexis, inaturalist.org
These little beetles don’t just diapause to escape cold temperatures. They also use diapause so they don’t starve since the insects they feed on typically disappear when it gets cold too.
Where Do Lady Beetles Diapause?
These critters will diapause in all sorts of places. The two main requirements they look for in an overwintering site are warmth and protection.
They need protection when they diapause because they are vulnerable to predators during this time. They will search for cracks and crevices in rocks, trees, and logs. They can wiggle into these places and hide for the winter.
Some of these critters will also burrow into the forest’s leaf litter to stay warm and protected when they shut down.
By inbetweenbays, inaturalist.org
Other species will be attracted to your home, or other man-made structures, to hibernate in during winter1. The multicolored Asian lady beetle (MALB) is the most common species that does this.
By Jacqui Geux, inaturalist.org
2. Aggregation
Some ladybirds can congregate together in very large numbers when they find a good place to hibernate. This mass gathering of insects is known as aggregation. They do this using a species-specific pheromone they release which attracts other individuals of the same species to them. These pheromones are actually made up of volatile molecules that other insects can detect using special sensors on their antennae!
When MALB starts releasing their aggregation pheromone, you can end up with hundreds or thousands of them all huddled together5. If you’re wondering what to call a group of these little beetles, it’s called ‘a loveliness of ladybugs’. Though, I don’t know if I would call hundreds of uninvited insects in my home lovely.
By Irvin Louque, inaturalist.org
When these little critters come together, it provides a layer of protection while they’re in diapause. They can excrete a liquid toxin from their leg joints which tastes and smells bad to predators. It usually only takes a predator eating a few of them to realize that they don’t exactly make for a tasty meal!
By hibernating in a large group, ladybugs hope that if a predator comes along, only a few will be eaten before the predator decides to move on.
3. Migration
These beetles will migrate for one of two reasons, to find food or to migrate in search of a place to overwinter.
These creatures can fly quite a long distance considering how small they are. They have been documented flying at speeds up to 60 kilometers per hour and flying over 120 km in a single flight session3. Even though they are capable of traveling long distances, most individuals will only migrate a few miles to find what they need.
The convergent lady beetles will begin to migrate to overwintering sites when food quality decreases or they begin to experience starvation4.
By Ken-ichi Ueda, inaturalist.org
How Do Ladybugs Fly So Well?
Ladybugs, like all beetles, have two sets of wings. Their forewings, called elytra, are the hard outer wings you can see when they aren’t flying. This set of wings provides protection and can be used during flight, like a boat rudder, to help the beetle steer.
Underneath the elytra, beetles have another set of wings (hindwings) which are membranous and much larger than the elytra. These membranous wings fold up to remain protected when the beetle isn’t flying. These are the wings beetles actually ‘flap’ in order to fly.
By Will Kuhn, inaturalist.org
When Will Ladybugs Wake Up
Temperature is the key factor driving when these critters wake up and migrate back after winter. Ladybirds typically won’t take flight until temperatures are above 55 degrees Fahrenheit2. The warmer temperatures become, the more active these beetles get in early spring.
By christine123, inaturalist.org
If you find yourself missing these wonderful little critters, you can rest assured that when winter is over, they’ll return in full force and resume munching on your garden insect pests.
References:
[1] Goetz, D.W., 2008, March. Harmonia axyridis ladybug invasion and allergy. In Allergy & Asthma Proceedings (Vol. 29, No. 2).
[2] Honěk, A., 1985. Activity and predation of Coccinella septempunctata adults in the field (Col., Coccinellidae). Zeitschrift für angewandte Entomologie, 100(1‐5), pp.399-409.
[3] Jeffries DL, Chapman J, Roy HE, Humphries S, Harrington R, Brown PM, Handley LJ. Characteristics and drivers of high-altitude ladybird flight: insights from vertical-looking entomological radar. PLoS One. 2013 Dec 18;8(12):e82278. doi: 10.1371/journal.pone.0082278. PMID: 24367512; PMCID: PMC3867359.
[4] Rankin, M.A. and Rankin, S., 1980. Some factors affecting presumed migratory flight activity of the convergent ladybeetle, Hippodamia convergens (Coccinellidae: Coleoptera). The Biological Bulletin, 158(3), pp.356-369.
[5] Wheeler, C.A. and Cardé, R.T., 2013. Defensive allomones function as aggregation pheromones in diapausing ladybird beetles, Hippodamia convergens. Journal of chemical ecology, 39(6), pp.723-732.
