Though it looks like it might be a beetle, this glamorous insect belongs to an entire different insect order than beetles....it's what is called a 'true bug'...a member of the Hemiptera order. Beetles are Coleopterans. These are a relative of stinkbugs.

This particular true bug is a nymph ('youngster', as Jean calls them) of the Harlequin Bug. These insects can be found on most of our veggie plants; melons aren't their favorite but certainly on the list of host plants.

Here is a link that might be useful: Harlequin bug

I just found a similar beetle in our garden, feasting on our winter arugula and mustard seedlings! Think it may be a 14-spotted ladybird beetle -- or Propylea quatuordecimpunctata - anyone know how to get rid of them??

The above insect is not a beetle. Perhaps you should post an image of yours for a definite identification. If the insect you've observed IS a 15 spotted ladybug, then it's not eating your seedlings, but is after aphids and other pests.

If the insect is actually munching on your plants, then you probably have a population of Harlequin Bug (but not a beetle), probably in various stages of development.

The above insect is not a beetle. Perhaps you should post an image of yours for a definite identification. If the insect you've observed IS a 14 spotted ladybug, then it's not eating your seedlings, but is after aphids and other pests.

If the insect is actually munching on your plants, then you probably have a population of Harlequin Bug (but not a beetle), probably in various stages of development.

The 14 spotted ladybug is not widely distributed in North America, yet. Where are you located? Let's ID BEFORE you worry about how to get rid of them.

Here is a link that might be useful: 14 spotted ladybug