Movies will often use live bugs on camera instead of CGI to make their story feel more real and to get your skin crawling. But getting these insects to do what you want requires lots an understanding of how they function. That's where Steven Kutcher comes in. He's an entomologist who has worked with insects on over 100 major projects including "Spider-Man, "Arachnophobia," and "Jurassic Park." We spoke with Kutcher about how he gets these tiny actors to do what the directors want and how no one gets hurt during the production. Following is a transcript of the video.

Narrator: Some of the biggest stars in Hollywood are some of the smallest creatures on the planet. Real live insects like spiders, locusts, and butterflies play crucial roles in many memorable blockbuster films. But getting them to perform on camera is no easy task.

Steven Kutcher: Rosie, lift up your leg. This leg. Come on. Oh see, she did this one. Oh, there she goes. And that's just a little trick of putting a little pressure on her back leg that causes her front leg to come up.

Narrator: That's Steven Kutcher. He's an entomologist and the go to guy for all things bugs in Hollywood. He's worked with a variety of insects on over 100 films in his career including "Arachnophobia," "Jurassic Park," and "Spider-Man."

Kutcher: Understanding insect behavior is really the key. It's not training them because you don't have time to train them in the film industry. When you work with insects, you wanna corral the insects. You wanna be able to control them.

Narrator: He's used a number of different techniques to get the bugs to move in the right direction involving lights, air, and temperature.

Kutcher: Let's say you're a bug. How can I make you move? Well, I could blow air at you, like 60 miles an hour air. You're going to move. I could light a little fire under you or set you on something that's really hot. You're gonna get up out of your seat and move. I could chill down the room.

Narrator: For example, let's take a look at one of the most famous and terrifying spider films of all time, "Arachnophobia."

Kutcher: The great thing about that film was it was before CGI. So we had to do everything real except for one shot.

Narrator: He devised a clever yet simple rig to get all the spiders where they needed to be.

Kutcher: They would say, "We want a spider to crawl into a slipper "from four feet away." So I came up with this idea of invisible vibrating wires. Chance of vibrating wires that you couldn't see, the camera couldn't see. But I could make the spider go directly to the spot I wanted it to go.

Narrator: Kutcher's first big Hollywood gig was on the "Exorcist II" and it involved working with three thousand live locusts.

Kutcher: There's a scene where James Earl Jones has to look at a cage of locusts and the locusts were all on the ground. But how do you move hundreds of locusts up on the screen? I said, "Get a light, a studio light that gives off heat "and shining against the side of the cage." And they did and all the locusts moved up onto the cage to be near the heat. Then they took the light away.

Narrator: In "Jurassic Park," Kutcher was the man responsible for the iconic dead mosquitoes in amber.

Kutcher: So it's supposed to be a mosquito. First, it's really a crane fly. And I put antenna from another insect on the crane fly. I took a bent insect pin and made it for its mouth part. I created the wings.

Narrator: And he worked with a live mosquito in the DNA Explainer video.

Kutcher: So I would chill the mosquito down so that it wouldn't move. And then I would drip honey on it. And then it got tumbled down with the honey.

Narrator: In the 2002 movie "Spider-Man," there's a scene where Peter Parker first gets bitten. Kutcher was actually above Toby McGuire with a paint brush.

Kutcher: And what the spider will do is it will crawl along the edge until it reaches this part and then it will hang on. And I would just tap it like this which would cause the spider to web down.

Narrator: While he says he rarely ever gets bitten or stung, he takes precautions to protect the other human actors. In "Roadhouse 66," Judge Reinhold is driving a car and I had to have a scorpion crawl over his shoulder. So I put a little cap on the scorpion's stinger that looked like the stinger so it wouldn't hurt him.

Narrator: And there's also a rule on set that no bugs are hurt during production. - In making of a movie, you can't harm a cockroach, or a fly, or a maggot. But if the fly flies to craft service, you can swat it.

Narrator: He can get some of his bugs from pet suppliers, but most he goes out and collects himself. And Kutcher's home is also full of bugs, by choice.

Kutcher: Right now, I have mosquitoes, crane flies, caterpillars in my refrigerator. The world is filled with people who do not like insects which is a great opportunity to teach those people the joys and wonders of all of the arthropods in the world and how you can relate to them. And when you understand how they work, the world is a better place.

Kutcher: To make the spider go, I just tap her back legs. And this gets her to crawl up. To make her stop, I cover her eyes. She has eight eyes. She's just looking for a dark place.