- We searched for meaningful comparisons of insect activity by day and by night.
- Our global analysis confirms there are indeed more insects out at night than during the day, on average.
- And now we know for sure, we can make more strident efforts to conserve insects and preserve their vital place in the natural world.
Building a global dataset of sleepless nights
- We narrowed these down to studies using methods that would not influence the results.
- For instance, we excluded studies that collected insects by using sweep nets or beating branches, as these methods can capture resting insects along with active ones.
- These include pitfall traps (for crawling insects), flight interception traps (for flying insects) and aquatic drift nets (for swimming insects).
Eventually, we honed in on 99 studies published between 1959 and 2022. These studies spanned all continents except Antarctica and encompassed a wide range of habitats on both land and water.
What did we find?
We found more mayflies, caddisflies, moths and earwigs at night. On the other hand, there were more thrips, bees, wasps and ants during the day.
- In these aquatic areas, there could be twice as many insects active during the night.
- In contrast, land-based insects were generally more active during the day, especially in grasslands and savannas.
- We also found insects were more active at night in warmer parts of the globe, where there are higher maximum temperatures.
Findings underscore the threats to nocturnal insects
Insects perform many vital “ecosystem services” such as pollination, nutrient cycling and pest control. Many of these services may be provided at night, when more insects are active. This means we need to curtail some of our own activities to support theirs. For instance, artificial lighting is detrimental to nocturnal insects.
- In the hottest regions of the globe such as the tropics, the warming trend may further reduce the activity of nocturnal insects that struggle to cope with heat.
- Read more:
Insects will struggle to keep pace with global temperature rise – which could be bad news for humans
The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.
