My dahlias are being destroyed!!!!!

Delhi, IA

Here are some blooms. They look really nasty, all chewed. I've counted over 20 bugs on one bloom, the whites seem the worst, or maybe they just don't show up as well on darker blooms.

Thumbnail by jamlover
Delhi, IA

And I have a terrible infestation of these. I assume cucumber beatles. Used Bayer systemic a week ago but didn't help yet at least.

Thumbnail by jamlover
Cincinnati, OH(Zone 6a)

Jamlover, the bug that is yellow with black spot is a good bug. that is a soldier beetle, he is not the one doing the damage. I haved no idea who is in the background.

Cincinnati, OH(Zone 6a)

I have never seen that green bug before. Hope someone will ID for you!!

Cincinnati, OH(Zone 6a)

try this if this is the green bug from your pics:

http://bugguide.net/node/view/13995

Cincinnati, OH(Zone 6a)

ewww this link will tell you about the damage they do
I hope I never see them here!!!

http://www.defra.gov.uk/planth/pestnote/diabrotica.htm

Delhi, IA

Sure looks like the dudes. Thank you kindly.

The northern and western corn rootworms are well-known insect pests of continuous corn grown in Iowa. Rootworms are beetle larvae that spend the spring and early summer in the soil eating roots of corn plants. Heavy populations of rootworm larvae are capable of severely stunting the growth of corn.

In mid-summer the rootworm larvae transform to adult beetles that are approximately one-quarter inch long and slender. Northern corn rootworm beetles are uniformly pale green and western corn rootworm beetles are yellow with black stripes. The beetles remain in the corn fields and lay eggs in the soil until mid to late August at which time they begin to wander.

Corn rootworm beetles wandering away from corn fields are frequently a late-summer pest in gardens where they feed on flowers and vegetables. They may become numerous on a wide variety of plants but seem most attracted to light colored flowers such as dahlias, roses, and others. Even small numbers of beetles can ruin flowers by feeding on the moist buds or petals. Rootworm beetles are also common in melon and pumpkin patches where they feed on fruit rinds.

There are no completely effective control methods for rootworm beetles on flowers in late summer. Insecticides sprays are of limited effectiveness and repeated applications are required for even modest impact. Unfortunately, insecticides applied to blooms may kill bees and other beneficial, pollinating insects. Screening highly-prized blossoms with cheese-cloth, nylon netting or other light fabric is one way to avoid attack but may not always be practical. Ultimately the number of beetles dwindles by late summer and they disappear completely with frost. Learning to tolerate a little damage is probably the most practical response.

Cincinnati, OH(Zone 6a)

I just found the same article that you posted.
I'll know to smushhhhh them if they come this way!!!!

http://www.ipm.iastate.edu/ipm/hortnews/2004/8-27-2004/crw.htm




lipm.iastate.edu/ipm/hortnews/2004/8-27-2004/crw.html

Delhi, IA

Thanks so much. Had a reply on the dahlia forum from a grower of cut flowers in northern Illinois and he confirmed our analysis. Isn't the net wonderful? We can share photos and solutions if there is any.

Dripping Springs, TX(Zone 8b)

try using diatomaceous earth applied with a duster,it works for my cucumber beetles and asparagus beetles, I do have to re apply rather frequently ,I don't know if it kills them but they seem to hate it and don't land on the host plants until it gets washed off

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