Are Stick Insects Native in the UK?

You can go to pet stores all over the UK and find stick insects. But, are stick insects native in the UK? That’s a question that new pet owners frequently ask stick insect veterans. As for the answer, it is ‘no’. Although a number of stick insects have become naturalized here, they are not native to the UK. The climate in most parts of the United Kingdom isn’t welcoming enough for them to thrive.

The few species that have established themselves in the UK are all found in South West England. The weather there is mild enough to allow their eggs to survive through the winter months. It is also not so hot in the summer as to endanger them. Anywhere else in the UK just isn’t hospitable enough.

Coming to the UK

In order for stick insects to have become naturalized in the UK, they had to have got here from somewhere. Where is that somewhere? Insect experts say New Zealand. Three of the entrenched species are native to New Zealand. They could have arrived in the UK in any number of ways.

The most likely scenario is that stick insect eggs made their way from New Zealand to the UK on imported vegetation. Eucalyptus and ferns are both good candidates as main carriers. Otherwise, there are plenty of other plants that could have carried the eggs into the UK.

Stick insects are so good at camouflage that it would be easy to miss eggs on vegetation. So it would only take one or two crops of plants to get the insects here. Under the right conditions the eggs would hatch, the nymphs would grow, and an adult population would be established.

Five Naturalized Stick Insect Species

With the history out of the way, let us address the “are stick insects native in the UK?” question from another angle. Let’s talk about the five species that have become naturalized here over the last hundred years or so. Remember that they all live in South West England.

1. Unarmed Stick Insect

Also known as Acanthoxyla inermis, the unarmed stick insect is perhaps the most prevalent. Some estimates suggest that up to 60% of all naturalized stick insects in the UK are unarmed stick insects. They are frequently seen in Cornwall. Colonies have also been observed in Devon and Dorset.

Interestingly enough, there are nursery records dating back to the 1920s that show unarmed stick insects fairly well entrenched at that time. With nearly 100 years of history behind it, the unarmed stick insect doesn’t show any signs of leaving.

2. Prickly Stick Insect

The Latin name for this insect is Acanthoxyla geisovii. It is definitely a species native to New Zealand and an insect that is quite prevalent there. The earliest record of the prickly stick insect in the UK dates back to 1909. Records from 1943 say that the insect was prevalent on the isles of Sicily at that time.

It can still be found on the Isles of Sicily. The prickly stick insect has also been cited in Cornwall and the Torbay region of Devon. Experts believe this particular species made it to the UK on ferns imported for the Isles of Sicily and their Treso gardens.

3. Mediterranean Stick Insect

The Mediterranean stick insect (Bacillus rossius) is not nearly as prolific as the previous two species we’ve talked about. This could be due to the fact that it hasn’t been in the country as long. Though no one knows exactly when it showed up, the earliest record we have is only from 2002. There is a colony on the Isles of Sicily along with another in Hampshire, which has been there since 2009.

4. White’s Sicilian Stick Insect

Known in Latin as Bacillus whitei, the White’s Sicilian stick insect is very similar to the Mediterranean stick insect in its biology. Also like its Mediterranean cousin, this species is not native to New Zealand. It more likely originates from somewhere in southern Europe.

Most sightings of White’s Sicilian stick insects are reported in Slough. They apparently have been in that region since the 1990s.

5. Smooth Stick Insect

The stick insect known as Clitarchus hookeri is native to New Zealand and has been here in the UK since the late 1940s. Interestingly enough, it is only found on the Isles of Sicily. Its territory in New Zealand is also limited, with the insects being found primarily in the Wellington region of the North Island and only along the eastern coast of the South Island.

All of the native New Zealand stick insects now found in the UK are fond of densely forested areas. That makes sense, given their diets. How they live in the wild lends credence to the idea that they made their way to the UK through imported vegetation.

How Stick Insects Lay Eggs

Stick insects are capable of laying lots of eggs during the summer and early autumn. But unlike some other creatures, great care isn’t taken in terms of where they are laid. In fact, they are simply dropped wherever the female happens to be feeding at the time. One of the results of this habit is that many of the eggs fall to the ground.

 

Sunny Stick Insect Eggs

Source: commons.wikimedia.org/wiki/File:Eggs_of_Sungaya_inexpectata.JPG

 

Imagine a forested area with a high eucalyptus canopy and a full bed of ferns underneath. It is easy to imagine eggs dropping from the canopy to the ferns. When those ferns are harvested, the eggs are harvested with them. The eggs go wherever the ferns go.

Here in the UK, naturalized stick insects have a fairly predictable life cycle. Eggs are laid in the summer and early autumn. They hatch in the spring, when the newly born insects immediately start climbing the first piece of vegetation they can find. All mature into adulthood rather quickly.

The average lifespan of a stick insect in the wild is usually only counted in months. Thus, stick insects rely on their eggs for continual propagation. Eggs must survive the winter because most adults do not. Perhaps that’s one of the reasons that nature dictates the eggs be dropped to the ground.

At any rate, you now know the answer to the question “are stick insects native in the UK?” They are not. But those species that have managed to entrench themselves here seem to be doing just fine. South West England appears to be more than habitable for at least five species.

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