I have a gardenia and there are tiny black specks falling from it onto the...

Asked December 16, 2013, 6:20 PM EST

I have a gardenia and there are tiny black specks falling from it onto the windowsill. It is obviously an insect of some kind dropping it's droppings but I can't find anything on the plant. Can you help?

Outside United States household pests houseplants gardenia horticulture

8 Responses

Thanks for contacting eXtension. Gardenia pests are traditionally the piercing-sucking type (aphids, scales, whiteflies, and spider mites) which either leave no frass (excrement) or excrete shiny, clear droplets called honeydew. In the honeydew, a black fungus will grow, but normally these areas are larger than black specks.

A few possibilities:
1) caterpillars (such as the Gardenia Bee Hawk caterpillar of Australia) will feed on this plant at night and hide during the day. There would be obvious loss of flowers/leaves in areas as the caterpillars grow. Bacillus thuringiensis is a biopesticide that is effective on younger caterpillars.
2) shot gun fungus is commonly found in mulched areas. When the spores are released, they are projected great distances from the ground on to siding, windows, etc. These tiny black specks are hard to remove, so if the specks you are seeing are easily brushed off, it is not shot gun fungus
3) plant bugs (e.g., lace bugs) leave small black, tarry spots on leaves and flowers
4) thrips also leave small black spots, but these are hard and shiny, and usually found under leaves or on flower.

Mark

Thank you younformyour help. I think I'll search for a caterpillar!

You are more than welcome! Some caterpillars are masters of camouflage, so look carefully. Holding a pad of paper (8" x 11") below some branches/stems and then gently rapping those stems might dislodge an insect, which will fall on your pad of paper. Good hunting!
Mark

Hi Mark

how big is this caterpillar likely to be?

judy

Judy, It will most likely be small, like a cabbage looper. The one in Australia, however, is very large, like a tomato hornworm. Mark

Hi Mark I found the little bugger last night and put him out in the garden. No 'frass' this morning. Thanks so much.

Judy

Awesome Judy! The 'little bugger' may have friends, as moths and butterflies usually lay many eggs in their egg masses. Mark

I'll keep my eyes peeled!