How to make a diagram of an insect from an insect

The first class I took as part of my entomology grad program is Insect Morphology, a class focused on memorizing the external body parts of insects. Needless to say, it’s a very difficult class, with us memorizing over 30 insect body parts per class or 60 per week. Additionally, we are responsible for making insect diagrams from actual insects, which is a pretty intense process, but one which I really enjoy. Knowing the parts of insects makes them much easier to draw.

Step 1: Find an insect

Chloe and I decided to share a grasshopper. We named it ‘Cuppy’. I cut Cuppy in half so I could fit it under the dissection microscope and now it looks very sad

It’s not hard to find insects when you’re surrounded by entomologists. Nate, our teacher (and my PI (PI stands for ‘principle investigator’- the PI of a lab is the head of the lab)), had a jar full of lubber grasshoppers, which I used for all my insect drawings, because I felt more comfortable butchering them than I would if I had borrowed a specimen from someone’s collection.

Step 2: Take an image of the insect


Taking pics of insects is harder than it sounds because it’s hard to focus on the whole insect at once and gets harder the smaller they are.

Because Nate does a lot of insect photography we have this rig set up in our lab. It is composed of a DSLR, attached to an arm that moves up and down and a stackshot.

The rig slowly moves the camera up or down while taking images at consistent intervals.


The resulting images are loaded onto a computer program which integrates all the images together to make one cohesive image where all the insect parts are in focus. Unfortunately, I can’t show you an image of that process because the computer we usually use for it started bugging out yesterday and we haven’t fixed it yet.

So far, being a scientist has been 20% repairing computers.

Step 3: Convert the image into greyscale and increase the contrast

colorhead (1)

Here’s my combined image. If I hadn’t done the stacking thing, you wouldn’t be able to see both the tips of the antennae and the legs clearly in one image. You can tell something funny happened to the picture because of the area around it’s head.

Chloe and I think that it looks like it’s posing for a school photo.

bwhead (1)

Once I had the image in black and white and had increased the contrast, I printed it out.

I spilled something pink on one side of the picture. Hopefully that doesn’t make it into my final diagram!

Step 4: Trace the image lines in sharpie

So this step is my own innovation and I’m very proud of it. Tracing over the parts of the image I think are the boundaries helps me later when I’m trying to trace the photograph onto another piece of paper, because at this point it’s pretty hard to distinguish the different sections of the insect, and tracing is even harder


Step 5: Trace the lines onto a new piece of paper

I should really use tracing paper for this, but I haven’t gotten around to bringing it in yet. I put the photo behind a piece of plain paper on a light plate and do my best to follow the lines I had marked earlier. I do this in pencil, so I can make corrections if I mess up. I don’t have an image of the result of this process- it didn’t look as clean as it does here.

Step 6: Check the real insect against the photo and drawing


So after I’ve done my best to trace the photo, I still have a lot of questions about what’s happening. At this point I refer back to my original insect. By examining it under the dissecting microscope I can make better guesses about which parts are which. I can try to determine which parts are membranes and which parts are sclerotic (hard plates made of chitin), and I can look for small features I might have overlooked (like ocelli (small, simple eyes) and setae (hairs)).  I will also consult the full color images I took during this process.


 Step 7: Attempt to identify and label the parts.

At this point, I’m ready to make some guesses about what I’m looking for. This is where having memorized insect body parts comes in handy. I also search the internet for diagrams people have previously done of similar insects.

This is my intermediary drawing. You can see I have only drawn the head; the dotted lines indicate the thorax, which I chose not to draw. I also only have outlines. For the purposes of making a diagram I’m not going to include any information about texture or color.


Step 8: Trace the intermediary image onto the final image

After going back between the microscope, the full color images, and the diagrams, I have what I think is a pretty good idea of what the insect looks like. But my intermediary drawing is really sloppy, so I want to trace it again to produce a clean, clearly labelled version. I put it on the light plate again and trace over the lines very carefully. You can see that I have stippled (put small dots in) some areas and some lines are lighter than others. The stippled areas are the membrane and the thin lines indicate sutures or sulci; ridged in the sclerotic plates rather than boundaries.


Here are all three of my images; my original photo with the traced lines, the intermediary image and the final image.

Step 10: Label the diagram.

Finally, I clean up the lines on my drawing, making sure all the widths are consistent and the lines are smooth (‘not sketchy’ is how Nate describes it). Then I add the labeling, trying to write neatly and using a small ruler to point to the objects. Finally, I add an indication of the insect species and order. I don’t give the species and genus name in this case because there are several species it could belong to and I don’t know specifically, so I use the common name.

And here’s my final product:

Apparently our scanner is really bad, so I took it with my phone