The Times Australia
The Times World News

.

NZ’s summer insects are packing up for autumn – here’s how our gardens can help them through the cold months

  • Written by Janice Lord, Associate Professor in Botany, University of Otago

Chillier mornings and higher heating bills aren’t the only signs of the changing seasons. Common insects, too, are having to adapt. One day we see them in our gardens and parks, the next they appear to have disappeared.

But most are still here – they’re just harder to find.

Overwintering is an adaptation that many plants, insects and other invertebrates undergo in temperate climates. It’s how they survive cold times of the year when food sources are scarce.

It’s similar to the way some mammals, such as bears, hibernate. But while hibernation involves an extended and deep dormancy akin to sleep, overwintering organisms are still active, just to a lesser extent.

Some alpine insects, such as wētapunga, can even tolerate being frozen solid[1] for days at a time, slowing down their metabolism until conditions become favourable again.

monarch butterfly on green leaf
New Zealand monarch butterflies have adapted to island life. Getty Images

The stay-at-home monarch

New Zealand’s monarch butterflies demonstrate how insects can adapt to new environments. In North America, they disappear for the northern winter, migrating up to 5,000 kilometres[2] from around the Great Lakes to the central Mexican volcanic mountains.

They arrive in huge swarms, with population estimates one year of around 380 million butterflies[3], clustering together to conserve energy.

Read more: Insects and spiders make up more than half NZ's animal biodiversity – time to celebrate these spineless creatures[4]

In New Zealand, however, the monarch has adapted to island life and does not migrate. We know this because, for 15 years, the Moths and Butterflies of NZ Trust tagged monarch butterflies in autumn and winter to track where they were overwintering.

The data collected showed no pattern of migration[5] or any common destination. Most recovered tags were still within the general area in which the butterflies were released.

New Zealand monarchs do show some similar behaviours to their North American counterparts, though. You might be fortunate to see a tree with a swarm of monarchs, usually on the tree’s northern side.

The butterflies stay active during winter, as temperatures allow. On a sunny day you will see them flying around, looking for nectar from flowers to top up their energy.

rake with leaves in garden
Leaf litter provides warmth and protection for overwintering insects. Getty Images

Leave the leaf litter

Overwintering in large numbers, however, is not typical of the way most insects survive the winter. Aotearoa’s native bees[6] are active only in the summer, when females forage to collect a nutritious “pollen ball” to sustain their dozen or so offspring underground during development.

Bee larvae will remain underground during winter, long after their parents have perished. They will emerge the following summer as the new generation of adults, never having met their caregivers.

While flowers rich in nectar and pollen are crucial for insects to forage when they emerge from overwintering, dead and decaying plant matter is the lifeblood of the invertebrate world[7] during autumn and winter.

Read more: NZ votes the red admiral butterfly ‘bug of the year’ – how to make your garden its home[8]

Leaf litter provides cover and nutrition for millions of insects and other microorganisms that cycle nutrients and soil, pollinate ecosystems and sustain larger organisms such as birds and fish.

You can help butterflies and other invertebrates survive winter by raking dead leaves onto the garden, rather than into the rubbish, and leaving seed heads on plants. Not only will this give these amazing ecosystem engineers somewhere to shelter, it will also help them return precious nutrients to the soil.

Plants such as Leucanthemum and Alyssum[9], which produce nectar-filled flowers in autumn and winter, can provide a top-up feed for butterflies and other pollinators during warm spells.

Native winter-flowering whauwhau, or five-finger (Pseudopanax arboreus), provides vital overwintering energy for insects. And kotukutuku (Fuchsia excorticata), though mainly bird-pollinated, is also popular with bees[10].

buble bees feedin on lavender
Bumble bee life cycles are linked to floral blooming seasons. Getty Images

Flight of the bumble bee

Not all insects overwinter. Colony and social insects such as bumble bees and honey bees follow characteristic phenological cycles[11], intricately and inseparably linked to floral blooming seasons.

Bumble bee queens initiate a colony underground and begin to produce workers that typically live for an average of 28 days.

As the colony deteriorates with age at the end of summer, the queen will shift from producing sterile workers to producing reproductive individuals. These male drones[12] and female gynes[13] will leave the nest to mate, while workers consume the remaining resources.

Read more: Why do bees have queens? 2 biologists explain this insect's social structure – and why some bees don't have a queen at all[14]

Around March and April you may see many dead bumble bees[15] on the ground. This isn’t necessarily cause for alarm – they have simply worked hard pollinating and have reached their natural life expectancy.

Meanwhile, newly mated queen bumble bees will now seek out new spots in which to begin colonies, such as vacant rodent and rabbit burrows. The queens benefit from the retained heat provided by undisturbed leaf litter, which also protects them from predators.

Eventually, our overwintering insects will emerge, often coinciding with the start of flowering and pollen production. But a changing climate can disrupt key plant-animal interactions[16] such as pollination. In the meantime, they will appreciate all the help we can give them as temperatures drop and the cycle of life turns again.

The authors gratefully acknowledge the help of the Moths and Butterflies of New Zealand Trust[17] in the preparation of this article.

References

  1. ^ frozen solid (predatorfreenz.org)
  2. ^ migrating up to 5,000 kilometres (www.fs.usda.gov)
  3. ^ 380 million butterflies (monarchconservation.org)
  4. ^ Insects and spiders make up more than half NZ's animal biodiversity – time to celebrate these spineless creatures (theconversation.com)
  5. ^ no pattern of migration (www.nzbutterflies.org.nz)
  6. ^ native bees (jandtlab.com)
  7. ^ lifeblood of the invertebrate world (xerces.org)
  8. ^ NZ votes the red admiral butterfly ‘bug of the year’ – how to make your garden its home (theconversation.com)
  9. ^ Leucanthemum and Alyssum (www.nzbutterflies.org.nz)
  10. ^ popular with bees (thisnzlife.co.nz)
  11. ^ characteristic phenological cycles (www.nzbct.org.nz)
  12. ^ drones (www.perfectbee.com)
  13. ^ gynes (www.amentsoc.org)
  14. ^ Why do bees have queens? 2 biologists explain this insect's social structure – and why some bees don't have a queen at all (theconversation.com)
  15. ^ dead bumble bees (www.bumblebeeconservation.org)
  16. ^ disrupt key plant-animal interactions (www.beeculture.com)
  17. ^ Moths and Butterflies of New Zealand Trust (www.nzbutterflies.org.nz)

Read more https://theconversation.com/nzs-summer-insects-are-packing-up-for-autumn-heres-how-our-gardens-can-help-them-through-the-cold-months-226206

Times Magazine

Building an AI-First Culture in Your Company

AI isn't just something to think about anymore - it's becoming part of how we live and work, whether we like it or not. At the office, it definitely helps us move faster. But here's the thing: just using tools like ChatGPT or plugging AI into your wo...

Data Management Isn't Just About Tech—Here’s Why It’s a Human Problem Too

Photo by Kevin Kuby Manuel O. Diaz Jr.We live in a world drowning in data. Every click, swipe, medical scan, and financial transaction generates information, so much that managing it all has become one of the biggest challenges of our digital age. Bu...

Headless CMS in Digital Twins and 3D Product Experiences

Image by freepik As the metaverse becomes more advanced and accessible, it's clear that multiple sectors will use digital twins and 3D product experiences to visualize, connect, and streamline efforts better. A digital twin is a virtual replica of ...

The Decline of Hyper-Casual: How Mid-Core Mobile Games Took Over in 2025

In recent years, the mobile gaming landscape has undergone a significant transformation, with mid-core mobile games emerging as the dominant force in app stores by 2025. This shift is underpinned by changing user habits and evolving monetization tr...

Understanding ITIL 4 and PRINCE2 Project Management Synergy

Key Highlights ITIL 4 focuses on IT service management, emphasising continual improvement and value creation through modern digital transformation approaches. PRINCE2 project management supports systematic planning and execution of projects wit...

What AI Adoption Means for the Future of Workplace Risk Management

Image by freepik As industrial operations become more complex and fast-paced, the risks faced by workers and employers alike continue to grow. Traditional safety models—reliant on manual oversight, reactive investigations, and standardised checklist...

The Times Features

Is our mental health determined by where we live – or is it the other way round? New research sheds more light

Ever felt like where you live is having an impact on your mental health? Turns out, you’re not imagining things. Our new analysis[1] of eight years of data from the New Zeal...

Going Off the Beaten Path? Here's How to Power Up Without the Grid

There’s something incredibly freeing about heading off the beaten path. No traffic, no crowded campsites, no glowing screens in every direction — just you, the landscape, and the...

West HQ is bringing in a season of culinary celebration this July

Western Sydney’s leading entertainment and lifestyle precinct is bringing the fire this July and not just in the kitchen. From $29 lobster feasts and award-winning Asian banque...

What Endo Took and What It Gave Me

From pain to purpose: how one woman turned endometriosis into a movement After years of misdiagnosis, hormone chaos, and major surgery, Jo Barry was done being dismissed. What beg...

Why Parents Must Break the Silence on Money and Start Teaching Financial Skills at Home

Australia’s financial literacy rates are in decline, and our kids are paying the price. Certified Money Coach and Financial Educator Sandra McGuire, who has over 20 years’ exp...

Australia’s Grill’d Transforms Operations with Qlik

Boosting Burgers and Business Clean, connected data powers real-time insights, smarter staffing, and standout customer experiences Sydney, Australia, 14 July 2025 – Qlik®, a g...