EASY Parasitic Alien Worm Costume




Introduction: EASY Parasitic Alien Worm Costume

About: My aim is to help you upcycle, remake, or sew! Or if you don't want to sew but would like to support artisans who do, visit my Etsy store: EmeraldRainbowProjct

My son saw a Mark Rober video about a costume that was an alien worm bursting out of his chest and he thought it was the best costume ever. He wanted me to make him one for that Halloween so we looked and looked for this video on Mark Rober's channel but could not find it for him to show me... we found all kinds of high-tech versions but no low-tech version... so we had to go on my son's memory.

Well, regardless of not having an example to see, it turned out pretty darn awesome and the most fun part of this Halloween costume is the gag component to it - he made people jump everywhere he went. Our good-humored next door neighbor said he scared the daylights out of her, as did many others. What could be more fun for a middle-schooler? :) I have to say as an on-looker, it never got old!

It was so much fun that his brother wanted to get in on the action and use it the next year - and Parasitic Alien Worm worked its magic again in a different part of the 'hood. The secret to getting the best reactions comes in the last step - so read on!

It was SUPER easy. In fact, if you need a last-minute Halloween costume, this would be it. My 6th grader did most of the work himself so it's a DIY easy enough for any kid to pull off him/herself! Since completing this Instructable, I searched to see if this idea was already here and yes, indeed, about 3 different versions already exist right here on Instructables.com. However, this would be the least complicated, most kid-friendly DIY version I've seen so read on if that's what you need.


  • A super long knee-sock (no-sew method) *OR* fabric & sewing machine (if you want an easy sewing project & don't want to have to buy new socks.) This is what I did.
  • Red paint, we used 2 shades - one that looked wet (shiny) even when dry.
  • Paintbrush
  • Plastic grocery bags or garbage bags
  • Hoodie (thrift store purchase)
  • Sharpie
  • Scissors


  • White powder (to make face look pale)
  • Dark eyeshadow (to make dark circles under eyes)

Step 1: Make Worm

If you are using a long knee sock then you are already 1/2 way done with this step.

If you want to sew your own worm, here are the super-easy steps:

  • Cut out fabric long enough to reach nearly up to the armpit, making sure you add 5/8" seam allowance all the way around. We wanted a green base for worm to look most alien-like. Brown would be great too.
  • I cut my fabric on the diagonal to give it a bit of stretch but, as it turns out, this isn't that important. Cut it any which way because the paint stiffens it up anyway.
  • Pin right sides of fabric together and sew around, leaving one end open in order to turn it right-side out.

Next draw any kind of scary face (including teeth) you might want on your alien worm with a Sharpie.

Stuff your worm with plastic grocery bags in order to prepare it for painting. This will prevent front and back sides from sticking together when paint dries. Plastic bags won't stick to the paint when dry like the cardboard we started out with.

Paint first side of worm with two (or more) shades of red paint, being sure that one of your paints is shiny so that it looks like wet blood when dry. (Both of my paints cost me a grand total of $3.) He painted a base with the non-shiny red and then went back and put the shiny paint over that in various places. Let dry overnight.

Once first side is dry, flip over and paint other side of worm in exactly the same way.

If you want to see it done, here's a link to the video on my channel. However, I have to warn you: Turn down your volume or you'll be blasted by the cringy intro.

Step 2: Prepare Hoodie

Turn hoodie inside out and draw lines where you will cut out the chest and then cut along these lines. I recommend a tri-cut of some kind - easiest to punch the worm out of and to put it all back together before saying "Trick or Treat" at the next house.

Next, paint the inside of these tri-cuts with the same red paint you used on the worm. This part has to look just as bloody as the worm itself.

Step 3: Enjoy the Scare!

Once all parts are dry, you are ready to don the worm & hoodie. Wear as close to a skin-colored T as you have under the hoodie (or nothing at all if that's comfortable and you can put fake blood on your chest).

Stuff the dummy arm with plastic grocery bags until you get it realistic looking. Place end of arm (where hand would be) in the hoodie pocket to make it look like hand is in pocket.

Give him/her a light powdering of white make-up on face and draw dark circles under his/her eyes with black, gray or dark blue eyeshadow.

Then have a blast making folks jump out of their skin!

Tip to getting the best reactions:

Put hand over chest or stomach to partially cover your cuts in hoodie. Then state in a low voice so they have to kind of lean in to hear a bit better, "[Groan], I don't feel so good..." Then let worm rip out of your chest. Get's 'em every time!

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    4 years ago

    I like this. I really, really like this.


    5 years ago

    That's a really fun costume idea!

    Threadhead Jude
    Threadhead Jude

    Reply 5 years ago

    :) it was so fun - lots of laughs


    5 years ago

    Such a clever, simple idea. Very nicely done!!