APHIDS

Major foliage plant hosts of aphids are Aphelandra, Dieffenbachia, Gynura, Hoya and Schefflera.

Aphids are soft bodied, pear-shaped insects generally less than 1/8 inch long. They feed by piercing-sucking mouth-parts and often can be found feeding on stem tissue of infested plants.

 

Oleander aphid, Aphis nerii Boyer de Fonscolombe, is a common pest of Hoya, Asclepias, Mandevilla, and Oleander.

 

                                    

Frequently the undersides of developing leaves are infested, and feeding causes distorted or stunted leaf development. Alert nursery personnel can often detect white skins shed by the developing aphids (see figure on the left below) on upper leaf surfaces. These shed skins are often the first sign of infestation. The green peach aphid, illustrated in this slide infesting the lower leaf surfaces of Aphelandra is one of the most common species found in commercial greenhouses.  These photos are of the green peach aphid, Myzus persicae (Sulzer).

 

                   

                                  

In greenhouses aphid populations, most individuals are wingless, but when colonies become dense, winged forms are produced which disperse within the greenhouse and establish new infestations. Infestations are often first noticed on plants adjacent to greenhouse vents or evaporative cooling pads, as these are the locations where winged migrants frequently gain entry. Under such conditions, winged forms caught in air currents are rapidly spread throughout greenhouses. Under greenhouse conditions aphid populations are all females, with each producing living young. Multiplication rates are greatly increased by the higher temperatures common within greenhouses.  These photos are of the melon aphid, Aphis gossypii Glover

 

                   

During most of the year in Florida, aphids give birth to living young.

 

                                 Photo by Elio Jovicich
Aphids have piercing-sucking mouthparts and thus feed my inserting them into the vascular system of the plant.  This is how they are able to transmit viruses. 

 

a                        b

  c

  d                            e

Often aphids are detected which are firmly attached to the foliage, swollen and brown in color. These are dead aphids which are referred to as mummies (see photo b).  These aphids have been parasitized and killed by a very small, beneficial wasp (see photos d and e). Some of these mummies contain circular holes in the upper body surface, and are hollow when crushed (see photo c). A tiny wasp adult had made these holes in order to escape from the mummy and attack other aphids.  If large numbers of these "mummies" are present (relative to live aphids) no chemical controls should be required to achieve control.  Sometimes aphids will have a reddish-brown color to them.  These aphids are in the process of turning into mummified aphids. In Florida greenhouses, the wasps that attack Aphis gossypii and make these papery mummies are usually Lysiphlebus testaceipes or Aphidius colemani.

 

Not all wasps turn the aphid into mummies that look like those picture in photos b& c above.  Some wasps turn the aphids black in color.  An adult wasp still makes a round exit hole in order to emerge.  These wasps are usually an Aphidius species.

 

This is a photo of the two different types of mummies and two healthy aphids.
More information on aphids can be viewed at "Insect and Related Pests of  Flowers and Foliage Plants". Click here to go there now!

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Lance S. Osborne: lsosborn@ufl.edu
Copyright 2016 [University of Florida, MREC]. All rights reserved.
Revised: Oct. 2015