Skip to main content
aphid

Q:  I have these small, black insects all over the buds of my hibiscus plant.  What are they and how do I control them? 

A:   Identifying the insects was easy since you brought a clipping of one of the buds into the Nassau County Extension Yulee satellite office plant clinic.  The insects are aphids, which are small pear-shaped creatures that pierce into the plant material and remove vital nutrients.  After looking at them on under the stereoscope however, we discovered something interesting. You mentioned you had not used any pesticide on the plant because you wanted to hear from me first.  What we discovered was the aphids were being eaten by two syrphid fly larvae.  These larvae are legless and look similar to other fly maggots but they vary in color and patterning.  Most have a yellow longitudinal stripe on the back.  It is fairly easy to see the difference between syrphid fly larvae and caterpillars.  Syrphid larvae have no legs and the skin is opaque which provides a “window” to see their internal organs.  The larvae can feed on hundreds of aphids in a month, which makes them very important for keeping aphids under control.  The presence of the syrphid fly larvae indicates a healthy eco-system in your yard.  I would leave well enough alone.  Applying pesticides to the plants would also destroy the syrphid larvae and the natural balance you have achieved would be disrupted.  Adult syrphid flies mimic bees as they have a black and yellow striped abdomen but they do not bite or sting.  The syrphid fly adults feed on nectar and pollen.  There are a few characteristics to watch for if you want to be able to determine if you have a fly or a bee.  Flies have large compound eyes but bees have simple eyes.  The antennae on the fly are short but bee antennae are longer.  Bees have two sets of wings, flies only have one set.