Step 20: Add the ant's other front leg by first lightly sketching a sloping line at the front of the thorax. When you get the slope and angle of the line right, add the two long segments for the leg. Add a couple of smaller segments at the bottom and a couple of spikes at the tip. Add a thin, small arc on top of the thorax for the top part of the middle leg on the other side. Add the rest of the middle leg under the thorax. The legs on the other side should be pretty equal in length.
Step 21: Draw the hind leg on the other side peeking out from behind the abdomen. Use the previous hind leg as a template and draw this hind leg the same way but slightly shorter. Most of the leg is behind the big abdomen, so you're only really drawing the top and bottom parts.
Step 22: For a cleaner look, erase as much as you can of the initial guide lines. Don't worry about erasing all of the guides. It's okay to leave some behind. Re-draw any final sketch lines you may have accidentally erased.
Final Step: Add some shading to your ant drawing for extra detail. Use a medium value for the antennae and a dark value for the eye. Leave a bit of the eye blank for shine. A lot of ant species have a only a single color on their bodies, so just use a medium value all over the body. Add a darker value at the bottom of the segments for shadow. This gives the shape dimension and volume.
Transition gradually from medium to dark so you don't have an abrupt value change. Vary the pressure on your pencil to get different degrees of tonal value. Add the value lightly at first, and then gradually build up to the level of darkness that you want. Use a lighter value at the top of the segments to represent shine on the ant's body. Shading can be time-consuming, so be patient and take breaks. It's always a good idea to use reference for a more accurate drawing.
Add a cast shadow underneath. This helps ground the ant so it doesn't appear to be floating. Don't forget to pause the video after each step to draw at your own pace.