As the nights get colder and we hug our loved ones closer, it’s good to remember humans aren’t the only animals who snuggle up because of unpleasant weather. Some penguins, for example, huddle for warmth, sharing their body heat to keep from freezing in Antarctic climes. Now we can add a not-so-cuddly creature to the list of animals who like to cuddle in unfavorable weather—the Madagascar hissing cockroach.
According to a new study in Ethology, these cockroaches like to snuggle up as well—not to conserve body heat in balmy Madagascar, but to conserve moisture when the weather is dry.
Biologist Lindsey Swierk, working with a team of undergraduate students enrolled in her animal behavior course at Binghamton University, split 32 adult cockroaches into different groups and varied the relative humidity in their enclosures. When conditions got dry, the two inch long cockroaches tended to pile up, creating a more humid microclimate within the heap.
It’s a behavior that’s been documented in insects before, mostly among smaller species and more vulnerable larvae, but this new research demonstrates even relatively beefy cockroaches lean on one another to stay hydrated.
Read more: “The Acquired Tastes of Foodies and Cockroaches”
“In general, insects can lose water pretty quickly because of their high surface area to volume ratios, and so humidity really affects their abilities to retain moisture,” Swierk said in a statement. “Our research shows that even larger adult insects, that may in theory be more resistant to low humidity than smaller or larval insects, still use aggregation as a flexible behavioral adaptation to reduce the risk of water loss.”
The research has important implications for ecology, as well. Climate change is lengthening the dry season in Madagascar, and cockroaches will presumably start banding together as a result. The increased grouping that comes with more arid conditions could boost cockroach competition—and even offer a more tempting target for hungry predators.
So hold your cockroaches tight tonight, it’s getting dry out there. 
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Lead image: Wiley Online Library
