OUr fall bearing raspberry plants ( 20' X 8' area 2 rows), received clouds of fruit flies 2 years ago. HOw can we get rid of them? We have blueberry bushes in the same area they dont seem to attack. Broccoli plants seem to be affected also.
Ramsey County Minnesota
There are two references below, one from the U and the second from Michigan State, concerning common fruit flies (Drosophila melanogaster), mainly in the house. However, whether inside or out, the cause is the same - overripe fruit or some sort of produce. It isn't clear how close your broccoli is to the raspberries. They may be on the broccoli due to its proximity. Keeping your raspberry patch clear of dropped fruit will help a great deal. Frequent picking should also help. Don't leave ripe fruit on the plants. There are also traps described in the following posts. It's a big job to keep a 20'x 8' area tidy but that will really help.
U of M Extension:
The common fruit fly has a cousin, Drosophila suzukii. Note the same first name. This little guy is invasive, coming into the country from Southeast Asia. It is known as the spotted wing drosophila. There are two U of M Extension references below. From your description, it does not appear that it is what you had 2 years ago. They lay eggs in non-ripe berries and the larvae eat the berries as they ripen. Little white worms in the berries were not mentioned. However, the spotted wing has reached Ramsey County. It is wise to be aware of it and know what you can do to fight the infestation if/when it arrives in your patch.