Introducing the “Australian Leaf Miners” iNaturalist Project

Are you using iNaturalist? It is one of the biggest online platforms for uploading records of observations of any thing in the natural world. If you are unfamiliar with iNaturalist, this page is an excellent read to understand how to use it .

As I embark on my PhD, I realised that there is so little information about leaf miners in Australia out there! But they are a group which can be explored by anyone who has ever picked up a leaf.

The more I learn about them the more I have become fascinated by them, and I think it’s a shame we don’t know more. I know there are people who are also interested in leaf mines (some of them have reached out to me!), so I have decided to launch the Australian Leaf Miners project on iNaturalist. Projects on iNaturalist are a good way of collating observations under a topic or theme, and will make the records easy to find for me.

In this post I will outline how to submit an observation to the project. It is intended for people who have never used iNaturalist in addition to people who are familiar with it. Happy snapping!

How to Submit an Observation to the Australian Leaf Miners Project

Firstly, you must be a member of iNaturalist to submit an observation. If it is your first time submitting an observation to iNaturalist, I suggest you follow this post about how to upload photos from your phone (through the app) or through the website. Then you can join the Australian Leaf Miners project to observations to it.

Take Photos of Your Leaf

Take photos of the leaf with the presumed leaf mine for your iNaturalist submission (I will make a post about how to tell if something is a leaf mine later).

If possible, take at least three different photos: top view (full leaf), bottom view (full leaf), and a back lit photo.

Two easy methods for taking back lit photos:

Leaf mine held up against the bright sky
Using a phone to back light a picture of a leaf mine
  • Hold the leaf (via the stem or branch) against the sky/sun. Perfect source of light!
  • Use a phone/torch/headlamp to light the leaf from behind.

A back lit photo gives a suggestion of whether a leaf miner is present, and how big it might be (useful information for my research).

Advanced: Close up photos of the “beginning” and “end” of a mine are useful too as the way a leaf miner exits the mine can be diagnostic, but this information is difficult to capture without a macro lens (I use an Olympus TG-5 camera).

Submit your observation to the “Australian Leaf Miners” project

You can add an observation to the project through one of two methods.

The Australian Leaf Miners project banner from the website

Method 1: Adding an observation by uploading it directly to the project by going to the project page as above and clicking “Add Observations”.

Method 2: Adding an observation to a project by typing in “Australian Leaf Miners” to the Projects field, often found on the bottom right hand side of the observation record.

Add additional information using the Observation Fields

A sample of some Observation Fields for this project

For every observation, there is an option to add Observation Fields. These are fields which provide useful information on host plant identity and may give clues on ecology. I have made the Host Plant ID a requirement (this is important information for identifying a leaf miner), but don’t worry if you can’t identify your plant, you can either:

a) Leave the Host Plant ID as “Kingdom: Plantae”

or

b) Upload a separate observation to get the plant identified. Useful types of photos to include for plant ID are discussed on this page. You can then link the observations by editing the description of the leaf mine observation to include a link to the plant observation, or you can use the Similar Observation Set Observation Field to link the records.

What about rearing out the larvae?

I welcome everyone to have a go at rearing out leaf miners. Whilst I personally don’t have a guide for how I rear my leaf miners out (yet), this one by Charley Eiseman is worth reading.

As for how to link your records, I suggest keeping track of timings of when individuals have pupated and emerged. I would put any larvae/pupae images on at the same observation and maybe make a separate observation for the adult. These can all be linked using the Similar Observation Set Observation Field. The method for linking observations is up to you, but the most important thing is that they are linked.

Be aware: In Australia, you must have a relevant collection permit for your state or territory which allows you to collect plant specimens (which is what leaf mines are). If collecting on private property, then you need permission from the landowner or caretakers.

If you rear out any moths then I suggest you also include your observations in the Lepidoptera Life Cycles (Australia) iNaturalist project.

What is a “leaf miner”?

Have you ever looked at a leaf and noticed some squiggles or blotches on it? Well that could be the work of a leaf mining insect larvae – there might be an insect in there!

A mysterious squiggle on a leaf – made by a leaf mining insect larvae!

I’ve been describing the subject of my PhD research as “a group of leaf-mining micro-moths”, but what does that phrase actually mean?

Leaf mining larvae inside a Eucalyptus sp. leaf
Leaf mining – it’s a lifestyle!
A diagram depicting examples of types of leaf miners (drawn by Lapsap_Art)

The term leaf miner actually refers to many types of insects, so there are leaf mining moths, flies, sawflies etc. It is a description of a life style, similar to the term “burrower” or “cave dwelling”. In the same way that “cave dwellers” can refer to many groups of animals that live in caves, “leaf miners” refers to many groups of insects that make mines in leaves. It just so happens that insects are the only things that are small and diverse enough to have evolved this lifestyle. Leaf mining insects include sawflies (Hymenoptera), beetles (Coleoptera), flies (Diptera) and moths (Lepidoptera). Of the leaf mining insects, a majority of the species are moths.

What do leaf mines look like? And how are they made?
A leaf mine in an Acacia sp. leaf. The dark areas are frass, and you can see the larvae in the middle of the clear patch.

Leaf mines can look quite different, depending on the type of insect and the species of the insect that made it. In general, when I look for leaf mines I look for a blotch or squiggle on a leaf, and then I hold it up to the light. If it is a leaf mine you’ll see some pellets (aka. frass aka. insect poop) in the leaf and if you’re lucky you’ll even see the larvae inside too. But what are they doing in there?

Growing up inside a leaf
A cross section of a leaf, with a leaf mining larvae shown in the epidermis (drawn by Lapsap_Art)

Leaf mining insects live and feed internally in a leaf. The female adult lays an egg on the outside of a leaf, and the larvae burrow (or mine) into the leaf and the larvae then feeds on the internal tissue of the leaf, resulting in some interesting shapes and patterns which may be observed on the outside of a leaf. Sometimes they spend their entire larval (and perhaps pupal) stage inside a leaf, and never move to a new leaf.

A leaf mining larvae feeding in the epidermis (as in the above diagram).

All insects have a larval stage. In butterflies, the larvae are commonly known as caterpillars and in flies the larvae are commonly known as maggots. When referring to “leaf miners”, it is really the behavior of the larval stage that is being referred to. The adult leaf miner is often a nondescript fly or moth that can be hard to identify as the adult form of a leaf miner (even with a microscope!).

What about the adults?
Here one of my leaf miners (a moth) exited the leaf mine and spun a cocoon on the lid of the container.

Good question! In general, once the larvae has finishing feeding it will develop into a pupa (e.g. spin a cocoon) and then eventually moult to become an adult insect (e.g. a beetle, fly, or moth). Many adult leaf miners do not feed, they have reduced or non-existent mouth parts and their aim is to disperse and mate. The females will then lay an egg on a new leaf and the cycle continues…

So what are “leaf mining micro-moths”?!
A specimen of the invasive oak leaf miner Phyllonorycter messaniella (Family: Gracillariidae) in a vial. (Yes it’s really there!)

The leaf miners I study are part of the moth family Gracillariidae, where a majority of the species are leaf miners. The adult moths are smaller than grains of rice, hence the “micro-moth” designation. Leaf miners in Australia remain quite understudied, so I’ll be updating this blog with some of the interesting findings I’ve made. Stay tuned!