Species: Cotinis nitida (Green June Beetle)
Who: Green June beetles are well known and hated by many gardeners; their other aliases are June bugs or June beetles. Though considered pests in both larval and adult stages, the grubs are known to be more destructive in most settings. The adults are usually just under an inch in length, with dull, metallic green wings. Gold accents can be seen on the sides, head, and legs. Grubs can be just over 1.5 inches long, with a chubby white body and brown head. The grubs can easily be confused with any others in the same family.
What: Considered one of the fastest-moving underground larvae, the fleshy grubs scoot on their backs using stiff bristles on their abdomens. They move along, feeding mostly on mold and humus, but are known to feed on root systems, causing significant damage. Though these larvae are often more associated with lawn grasses, damage has been reported on a variety of vegetable and ornamental plants, especially when they’ve been mulched. Most visible damage is done by the adults on ripening or damaged fruits. They can gouge healthy fruits to feed and may bury themselves completely. Their peculiar odor and excrement can also ruin otherwise edible tomatoes.
When: Adults begin laying eggs in late summer. Two weeks after eggs are laid, the grubs begin hatching and feeding, remaining active until winter, where they go into diapause as almost fully grown grubs. As spring approaches, they actively start feeding and growing again. They then pupate and emerge as adults beginning in May through the end of the summer, with most adults emerging in June, giving them their common names.
Where: Green June beetles are found in North America, with the largest populations located in the southern range.
Why: The larvae prefer feeding on decaying organic matter in the soil. Compost piles, manure, and mulch can attract adults to a garden, where they then lay their eggs. Rotting fruit, including tomatoes, can also attract these beetles.
How: Usually present in small numbers, these beetles aren’t usually a concern for tomato growers. But infestations do occur and can be detrimental. The easiest way to control these is starting with the larvae, who are susceptible to milky spore disease (Bacillus popilliae). This is available commercially and can take full effect in two or three years and last up to 10.
Lauren’s Notes: These beetles are actually quite gorgeous, especially their shimmery undersides! They are often confused with fig beetles, Cotinis mutabilis, which are far less destructive, particularly to tomatoes.