Larvae of the Southwestern Squash Vine Borer can rot a healthy plant from the inside out without being seen.
Common to states in the Southwest and Mexico, sightings of Southwestern Squash Vine Borer Moth should put gardeners and farmers on the defensive. The adults do not harm plants, but their larvae can decimate a crop in under a month. After mating, female moths lay eggs on the stems of gourd, squash, and pumpkin vines. The emerging larvae bore into the stem and live there, eating the inner stem tissue (pith) as they grow. The white, wormy larvae remain hidden during this life stage and emerge as nymphs after they pupate. Signs of infestation include leaf wilt, then stem rot which expands to other stems and kills the plant.
When dealing with Southwestern Squash Vine Borers, the best defense is a good offense. Preventing adults from contacting the plant means the worms cannot get near their food source. Covering vine plants with row cover is effective. Employing traps to catch/kill moths may help reduce the possibility of egg-laying. Cutting off stems that appear infected can curb the spread of the larvae to other healthy branches, thereby saving the whole plant.
Scientific Name: Melittia calabaza
Butterfly or Moth
Size (Adult; Length): 12mm to 15mm (0.47in to 0.59in)
Note: An insect's reach is not limited by lines drawn on a map and therefore species may appear in areas, regions and/or states beyond those listed above as they are driven by environmental factors (such as climate change), available food supplies and mating patterns. Grayed-out selections indicate that the subject in question has not been reported in that particular territory. U.S. states and Canadian provinces / territories are clickable to their respective bug listings.
Butterfly and Moth Anatomy
Antennae: Butterflies and Moths have a pair of antennae on the head used as sensors.
Head: The head is home to the insect's eyes, antennae, and proboscis.
Thorax: Home to the three pairs of legs as well as vital internal organs.
Abdomen: Contains vital internal organs such as the heart(s) and reproduction facilities.
Forewing: The upper, forward wing pair used for flying.
Hindwing: The lower, rearward wing pair used for flying.
NOTE: Butterflies and Moths are part of the Lepidopteran order as they share many similarities.