Marin Rose Society

FAST FACTS - CUCUMBER BEETLES
by Nanette Londeree, Master Rosarian

SIGNS

Shiny, greenish-yellow six legged insect, about 0.25 inch long, with black heads and long antennae

Striped or spotted adults, depending upon species

Whitish, slender larvae with three pairs of short legs; the head and tip of the abdomen are darker

SYMPTOMS

Shoots and blossoms that exhibit damage

Scars on soft fruit

Appearance of mosaic virus or wilts in cucurbits

CAUSE

Western spotted cucumber beetle, Diabrotica undecimpunctata

Western striped cucumber beetle, Acalymma trivittata

OPTIMAL CONDITIONS

Over winter as adults in weedy areas

Move into planted fields and gardens as soon as plants start to come up

Several generations a year

Before cucurbits are available, subsist on the pollen and petals of many plants

Pests of many plants including cucumbers and their relatives (squashes, gourds, and melons), beans, peas, corn and blossoms of several wild and cultivated plants; potatoes, beets, tomatoes, eggplants, and cabbage, roses and dahlias

TREATMENT

Prevention:

Maintain good garden sanitation

Dust diatomaceous earth around the base of plants to kill larvae emerging to eat and also create a barrier to egg laying

Knock, shake, or hand pick beetles off plants and out of flowers

For most vegetable gardens, place protective cloth over emerging plants and remove it when plants are old enough to tolerate damage

Maintain a diverse garden that includes general predators and parasites; birds, parasitic wasps, soldier beetles, and tachinid flies

Elimination:

Pyrethrum and rotenone sprays

Pesticides such as Adios® that combine cucurbitacins as a feeding stimulant with a small amount of the pesticide carbaryl (Sevin ™)

GOOD GUY / BAD GUY?

A very bad guy in the food garden as they girdle stems by gnawing on the tender shoots of seedlings, feed on blossoms and leave scars on the fruit; larvae injure plants by feeding on roots and tunneling through stems, and transmit deadly diseases - mosaic and bacterial wilts

It is more of a nuisance pest of roses

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FAST FACTS - CUCUMBER BEETLES by Nanette Londeree, Master Rosarian

FAST FACTS - CUCUMBER BEETLES
by Nanette Londeree, Master Rosarian