Foe!...... until its not.....

I feel like by now anyone reading posts on this thread are beginning to see a trend in the "friend or foe" classification for anything with the word "worm" in it. And that's because worms are complicated. Or at least when the worm is the larva of a moth they are complicated. This is because as larvae, worms are very destructive to plants. And moth's tend to have host plants that are also our prized food producing plants. As if moth's didn't already have a bad rap for being ugly butterflies!

Back to Melonworms.

Melonworms, or Diaphania hyalinata Linnaeus, are the larvae of the Melonworm Moth. Many Florida gardeners have problably encountered Melonworms at some point or another. They host on many plants that are popular among vegetable gardeners. Host plants include most plants in the cucurbits - the gourd family. So,

Zucchini

Squash

Pumpkin

Cucumbers

Watermon

and other Gourds

Larvae begin as colorless young instars and eventually will become green in color. In the 5th instar, two white dorsal stripes appear that help in identification of this worm. Prior to pupation, they will spin a silky substance that rolls the leaf over helping protect the cocoon from predators. This behavior can trick some people into confusing them with leafrollers.

Cocoons are easy to find in the rolled up leaf. They are a reddish-brown color. Adult moths will emerge in around 9-10 days.

Damage by Melonworm larvae are primarily on plant foliage. Typically leaf ribs are left intact. If the infestation is severe, the foiliage may be reduced enough that the larvae turn their appetite to fruits. In more mature fruits, damage is usually limited to the surface of the fruit. Sometimes the larvae may even burrow into the fruit. This feeding behavior leaves scars on the fruits contributing to another common name given to these larave - "rindworms".

Management of Melonworms is best done by allowing natural predators to do their job in the garden. There are many natural predators including predatory wasps, Soldier beetles, assassin bugs, and other predatory insects along with birds and lizards. Once predators have found larvae on your plants, they will provide constant patrol for more.

If infestations are severe treatments of Bacillus thuringiensis (B.t.) are effective. B.t. is a harmful bacteria specific to worms and caterpillars but will not harm other insects. This is especially important when applying to cucurbits as they rely heavily on pollination to set and hold fruit. Other chemicals that are not target specific may kill beneifical pollinators which will reduce yields. Not to mention kill beneficial insects in the garden.

Prevetative measures include covering host plants with netting so that adult moths will not be able to lay eggs on leaves. Another technique is sacrificial planting. This involves setting aside a few host plants to relocate larvae to. The relocated larvae will feed on the sacrificial plants while your "designated winners" thrive and produce fruit. This tehcnique also allows for predatory insects to stay involved in the garden.

Do you have any experience in dealing with Melonworms? Join the conversation below!