They definitely can be. They spread disease and suck the life right out of your plants. It's nice that you see some ladybugs, but sometimes they need some help. Spraying the undersides of the leaves with blasts of water every few days(just like aphids), helps bring down the populations to manageable numbers. Next would be insecticidal soap, and then neem oil. Of course, if money isn't a problem, then order some lacewing larvae for a couple of releases. Try to plant some flowers(herbs) that attract them in the future like dill, coriander, cosmos, tansy, yarrow, etc.

Kevin

Donna, whiteflies can be a terrible challenge. I disagree that spraying them with water helps to control them. The eggs and nymphs, tucked away under the leaves, are pretty fixed in place.

Do you have any horticultural oil on hand? There are some good summer weight products on the market. You could mix a little in a spray bottle and direct the mist to the underside of the leaves. Hort oils are considered acceptable for organic growers.

Neem oil is very useful in that it works as an anti-feedant, as a growth regulator for those insects that feed on the plants, and also smothers the eggs and nymphs just like a plain hort oil.

If I had a bad WF problem on my tomato, I'd use Neem.

Agree with Rhizo1: Though water blasts can HELP bring DOWN populations, I've never controlled them without MORE help either with a pesticide or bio-control.

Kevin

Thanks, y'all. Got on Amazon and ordered Neem and a horticultural oil. I have never used them, but I assume there will be directions on the bottles.

Yep. However, I have found that the water blasts in the beginning really help. Also, the directions call for weekly and then bi-weekly intervals. In the beginning 2 weeks, I up the ante because of the rapid rate of re-popualtion of whitelfy. So, for the 1st week, water blasts every 3-4 days, then neem treatments ever 3-4 days for 2 weeks. After that, populations are usually low enough to control with bi-weekly treatments. Yellow sticky traps used in conjunction are also effective. But, lacewings are truly the best, so think about planting some flowers to attract them.

I just posted a thread that may help.

Kevin

Here is a link that might be useful: Beneficial insects/IPM