Quirks & Quarks

Cannibal insects get hungrier in a warming climate

Rising temperatures increase the frequency of cannibalism in damselflies, and likely many other species.

Damselflies are similar to dragonflies, only smaller, and are found all over the world.  They lay their eggs in the Spring on the stems of wet grass near ponds.  In September, they emerge as damselflies, completing the annual cycle.  But a new study by Denon Start, a Phd candidate from the Department of Ecology and Evolutionary Biology at the University of Toronto has found that rising temperatures are having a negative impact on that cycle

Damselflies — already known to be cannibalistic —  are eating other damselflies with greater frequency.  Higher temperatures increase activity among damselflies, which also increases the number of encounters with other damselflies.  More encounters results in increased instances of cannibalism.  Also, as temperatures become warmer, the eggs hatch according to proximity to the pond.  This results in some damselflies having as much as a two-week head start in terms of growth, which also increases the frequency of cannibalism.  Among cannibals like damselflies, the smaller insects are very easy prey for the large. 

The researchers believe that an increase in cannibalism due to climate change may also be happening with many other species.