Hello, Tedjiart:

Let's see where you can improve:

Organic forms

I feel like these sausages forms were drawn in a rush. Some edges are almost as spiky as a triangle. Remember that sausage forms should be two spheres joined by a cylinder. Ellipses are not wrapping around correctly, they should feel as if the stroke will continue inside the form, you have a lot of ellipses where one of the ends stops pointing outside of the form. Your lines were smooth so good job on that.

Insects

Your construction was great. You built on top of the foundation and applied correctly line weight to communicate the lines hierarchy.

I think you struggle a bit with legs, maybe because of the previously mentioned mistakes on organic forms. Also, it could be the outcome of rushing through the less interesting parts of the drawings (if it's the case, please stop, don't skip your legs day). Try to construct over the legs too, adding a bit of detail as you did with the tarantula helps a lot.

As an improvement, I would add some background details to help both the viewer and yourself believe the 3D illusion. This is because some of your insects have their legs flying around in the air and it's hard to imagine where they are. There are cases in which this is not a big deal, the grasshopper for example feels like he is standing on a flat surface. On the other hand, the mantis feels like is on top of something and would be a great improvement to show it.

Drawing the shadow silhouette could be great too so you can practice a great technique for shadowing without having to worry about filling the inside of the shadow.

Verdict

I think you are prepared for lesson 5. In the end, these lessons are different approaches to construction so you can pick the one that works for you.