Houseplant pest question

Hi, please point me in the right direction if this is the wrong place to ask. I'm new here and still finding my way around. I am having a problem with thrips. At least, that's what I think they are. This bug is black, with tiny legs on one end of an s-shaped body and very small, about 2mm long (I studied it under a magnifier). They crawl on the leaves of my plants and leave brown, dead patches where they have been. Malathion works but I want to be careful what I spray indoors. . . insecticidal soap doesn't work and I have had some success with pyrethrins but that's messy and the bugs reappear after a month, even if I spray every two weeks to catch the nymph stages. They can jump, too and migrate to other plants. They especially seem to enjoy munching on my amaryllis and other tropicals. :(

Any suggestions would be most appreciated.

From your description I'm not sure they're thrips, but if they are they are good at hiding in various places on the plant so you're probably just not catching all of them when you spray. Here's some info on thrips, maybe this will help you figure out if that's what you really have or if it's something else. If it is thrips they recommend some ways to control them, and if it's not thrips it's better to find out what they are first before recommending pesticides. http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7429.html

Hmm, you may be correct. . . none of those I've seen have wings or look like the ones on the page you reference. I will try doing some more online research and possibly get a photo, but they are so tiny, I'm not sure if my macro lens will do it. Thanks for your help!

Thanks ecrane3, they are thrips, but my research so far hasn't led me to which one of the over 5000 species it might be. I trapped one in a small plastic bag, studied it with my jeweler's loupe and drew this picture. The wings are there but they are so tiny that I almost missed them. All the other signs are present, leave discoloration, tiny fecal spots. . . I thought they were hopping but they actually fly! I guess pyrethrin is best but it's messy and sticky. I might have to quarantine the plants, clean the whole window area and try again. I have put the amaryllis away for a dormancy period but I added some crushed mothballs to the pots. Hope it helps!

Good way of isolating plants is to put a cover of light fleece from garden store over the plants, this fabric allows light in, you can add moisture to the foliage and it wont be heavy on the plant. you can make a tent from canes, use the fleece and tie it at the bottom at the pot the plant is in, do thid after you have sprayed and it prevents the flying insects moving house to another plant.
As for the spray treatment you did before, it is always best to re-apply the spray after a week or so to make sure non survive, at the first spray, there may have been unhatched eggs laid and the spray wont have got these flies, so next spray will get them too.
just keep a close eye out for new flies each week rather than a months time when the infestation has got hold again, but you are doing the right thing, just stay really vigilant. good luck. WeeNel.

Another idea that I use with my gladious is after I dig them up in the fall and let them dry usually about a week, I put them in a paper grocery bag and add Dr scholls foot powder, (the kind that kills athletes foot )and shake. I leave them in the bag for the winter and plant in the spring. no thrips, something in the powder kills them, you might try sprinkling some on the affected plants.

I googled "life cycle of thrips" and found the time that they stay as eggs is 14 - 16 days. If you spray every two weeks for a total of 3 times, you should kill them all.

I didn't look any farther, but, hanging those sticky traps around the affected plants may help too.

G'luck,
Nan

Thanks all, I will try the suggestions you've provided. I've learned a few things surfing the net as well. I think it is a form of greenhouse thrips, possibly Heliothrips femoralis. They lay their eggs on the leaf undersides and probably in the dried layers of my amaryllis bulbs. The adult stage can live up to 45 days, so they do a lot of chewing! I will try a combination of the quarantine, storage, clean and spray cycles as noted. Hopefully it works. I also learned that they can be virus carriers too, so I am even more determined to be rid of this pest!

Have your plants with the insect problem ever summered outdoors?

It's quite likely the pest was introduced by bringing a new plant into the environment. . . I suspect this one is an indoor variety because when I move infected plants outdoors, they seem to disappear. They prefer certain plants and maybe they move on to something else. I've been dealing with this on and off for over a year and some of the plants can't be moved outdoors, but that is an option to consider.