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| Squash vine borer, Melittia cucurbitae - Kevin Firth |
Kevin Firth sent me this photograph of an insect he found on his porch. It looks at first glance like a wasp with a serious case of abdominal obesity that has obliterated its waist. Kevin assured me that it really is a moth, the
squash vine borer,
Melittia cucurbitae.
The adult is approximately
2/3" long (16 mm) in length, with a wingspan range of 25 to 38 mm. The front wings
are covered with scales that reflect a metallic green to black
sheen. Large portions of the hind wings lack scales, making them look
clear. The abdomen is covered with conspicuous orange to reddish hairs, with a row of black dots.
The
hind legs are covered with long black hairs inside and orange hairs
outside (Bauernfeind and Nechols 2005). Females are larger and less
colorful than males, with wider abdomens.
While most moth species are active at night, squash vine borer adults (and many members of the family
Sesiidae) are active during the day, resting in the evenings. The adults can be observed during the day feeding on
nectar.
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| SVB eggs on zucchini - CC |
This is the adult form of a larva universally hated by gardeners. The adult moth mates and lays its eggs on host plants within 24 hours. The innocent looking eggs are laid on members of the
Cucurbita family (zucchini and related squash).
In 1-2 weeks they hatch and then immediately bore into the vine stalk where they go through four instars, moving down the center of the stalk, killing the plant. Unlike other garden pests like the tomato horn worm that at least have the decency to eat the leaves, these pesky critters kill the entire plant at ground level.
Many more details about SVB including management practices are at
Entnemdept.ufl.edu. For a more satisfying method, the
Old Farmers Almanac suggests you spot "entrance holes and 'sawdust' then insert a wire and thread it through the stem for some distance to kill the inside larvae." I can hear the screams now.
