With spring melons rapidly maturing, now is a good time to step up your scouting for Lepidopterous larvae feeding on developing and mature fruit.  Beet armyworm (BAW) and cabbage looper (CL) are becoming more abundant throughout the area. I’ve had reports of BAW egg masses and larvae showing up in alfalfa and cotton, and our BAW and CL pheromone trap counts increased sharply over the past 2 weeks, particularly in Dome Valley and Yuma Valley where traps peaked at over 40 moths / trap / night. Corn earworm (CEW) trap counts are lower, but they have been steadily increasing over the past month. So be on the lookout for these Lep species, all of which can cause significant economic damage to smooth and netted melons by feeding on developing fruit in the following manner.    
BAW: Although primarily foliage feeders, larvae will cause economic damage to watermelons and other smooth skinned melons by attacking immature fruit. The injury caused by fruit feeding is superficial, but results in cosmetic blemishes left on mature fruit (see image below) and fruit rot that may occur from secondary pathogenic organisms that enter the wounds.  The larvae will occasionally develop inside the fruit, causing abnormal development and abortion of the fruit. 
CL:     In cantaloupes, feeding on crown leaves often leaves a ragged appearance. Although this damage may not be yield limiting, larvae may move to the mature fruit and feed on the netted surface causing cosmetic blemishes (see image below).  Similarly, in watermelons and honeydews larger larvae will feed on the outer rind of maturing fruit causing large silver-colored or darkened scars.
CEW: Damage to cantaloupes and watermelons is not common, however larvae may feed on foliage and burrow in the stem. When larvae are present, they may feed on the developing fruit. Larvae are known to begin to burrow into fruit, feed only for a short time, and then move on to attack another fruit. 
Monitor fields by checking developing fruit for larvae and feeding damage. Treat with insecticides if feeding is observed on the fruit, or larvae can readily be found feeding on leaves. You have several options for controlling these Lep species.   It’s always best to spray when the populations beginning to build, as larvae often feeding on the melon near the soil surface and are difficult to reach with insecticides. To conserve natural enemies important for suppressing other pests (leafminers, whiteflies) consider using a selective insecticide (e.g., Intrepid, Coragen, Dipel/ Xentari). If whiteflies also require control, consider using Exirel or Minecto Pro, or tank-mix with a whitefly material (e.g., PQZ, Sefina, Venom/Scorpion, Courier, Oberon).   It is recommended that you avoid using Radiant or Lannate to prevent unnecessary exposure to western flower thrips. Whichever product you use, be aware of honeybees and other pollinators in or around melon fields. If bees are present, be sure to carefully read labels and determine bee safety of a product before making an application in a melon field.  For more information visit Lepidopterous Larvae Control in Desert Melon Crops 2024.