insects

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It’s a very pretty but deadly plant. Alpine sundew is a carnivorous plant that grows in sub-alpine and alpine areas of New Zealand. To supplement its diet it catches small insects, dissolves them and absorbs the “meaty” nutrients.

Not unlike an insect, I became attracted to sundew by the “dew drops” that were glistening in the sunlight. On my first encounter with this unusual plant, I dropped everything and laid down flat on my tummy to have a close look. Since the plant is quite small—the leaves are often no longer than 50 mm—it’s the only way to examine a sundew’s intricate details and fascinating features.

The fleshy leaves are covered in hair-like tentacles that secrete drops of sweet mucilage (before you ask, no, I didn’t taste it) which lures unsuspecting insects.

I have yet to observe the actual trapping of an insect. Although from what I’ve read, once an insect lands on the plant, it becomes trapped by the sticky dew drops and dies within 15 minutes, either as a result of exhaustion or, when it becomes completely wrapped by the sticky substance, by asphyxiation. The plant then secretes enzymes that dissolve the insect and free up its nutrients, ready for absorption by the plant’s leaves. What a crafty way for a plant to receive vital nutrients that are missing from the habitat’s poor soil!

Alpine sundew - Drosera arcturi

Alpine sundew–Drosera arcturi.

Alpine sundew - Drosera arcturi

Sunlight makes the leaves glow red.

Alpine sundew - Drosera arcturi

Without direct sunlight the leaves appear brown.

Alpine sundew - Drosera arcturi

An individual leave…

Alpine sundew - Drosera arcturi

…with glistening “dew drops”.

The scientific name of Alpine sundew is Drosera arcturi. The latter part of the name means “of Arthur”, derived from Mount Arthur, a locality in Tasmania, where Drosera arcturi also grow natively.

To come back to the question “how do you like your meat”, my guess is that Madam or Sir Drosera likes it “quite well done” to “well dissolved”.

On a recent tramp through the beech forest at the head of the Fyfe River Valley, I noticed a beautifully marked beetle on the forest floor. It sat there patiently while I zoomed in on it with my camera. Upon my return home I referred to Andrew Crowe’s comprehensive insect photo guide Which New Zealand Insect?, only to find that the beetle wasn’t listed.

The closest match appeared to be the Striped Longhorn (Navomorpha lineata), aka Candy-striped Longhorn that supposedly lives in the North Island only.

A search on the Web didn’t shed any light on the longhorn’s identity either. I then contacted Ian Millar, Technical Support Officer for Invertebrates at the Department of Conservation in Nelson, who responded, “The beetle is a longhorn, probably from the genus Navomorpha but a different species from lineata. I’ve come across this type of thing before in the South Island and have the odd example in my reference collection.

I can find references to at least five species of Navomorpha on the internet, but some of these date from the early 1900s when minor variations tended to be interpreted as a new species. As far as I know this group has not been subjected to a review in the past 30 or 40 years, making the taxonomy a bit suspect. The same actually goes for the whole New Zealand longhorn beetle fauna, the taxonomy for much of which dates back to early last century or late 19th Century. There are no or few published reviews or recent taxonomies, making it a difficult group to get to grips with. For this reason it’s a group which I know very little about.”

Thank you, Ian.

Well, there we have it, it’s a mystery longhorn beetle!

Longhorn Beetle

Its likely cousin, the native Striped Longhorn in the North Island, appears in late spring and summer, flies during the day and eats pollen. The grubs tunnel into live trees and shrubs, carrying yeast in their guts to aid with the digestion of the wood. Many grubs fall victim to the Lemon Tree Borer Parasite (Xanthocryptus novozealandicus), a native wasp who lays her eggs inside the grub, thereby naturally controlling the wood boring longhorn.

If you, or someone you know, can solve the mystery longhorn’s identity, please leave a comment.