Genus Glycaspis
White Lerp Insect
White Fibrous Lerp Insect
Genus Spondyliaspis
Shell Lerp Insect
Genus Hyalinaspis
Clam Lerp Insect
Clam Fibrous Lerp Insect
Brown Clam Lerp Insect
Genus Acizzia
Wattle Plant Lice
Other Psyllids


Cowpea Aphid - Aphis craccivora 

Family Aphididae

This page contains pictures and information about Cowpea Aphids that we found in the Brisbane area, Queensland, Australia.
Aphid colony, body length 1-2mm
This aphid is known as Cowpea Aphids or Cow Pea Aphids. During the spring season on the hibiscus plants in our backyard, we find this aphid. They are grayish-black in colour. They are one of the famous pest, although they seem not doing much harm to our plants. Their host include those plants in Malvaceae and Fabaceae.
We have three hibiscus plants in our backyard, the red, pink and yellow. The three plants are close to each others. The aphids only attack the red hibiscus. We can sometimes find one or two aphids on the yellow and pink plants but never see a colony. 
The aphids colony expanse very quickly in early spring. They feed on young shoots and flower buds. We also found at last five different predator species feeding on the aphids in mid spring. 
wpe11.jpg (27896 bytes)
In the above 1st photos, a new aphids colony is just started on this flower bud. Nymphs progress through five nymphal instars stages. Checked carefully we can see five different body size. The pale white fellows are the newly born aphids. The light-grey ones are the 2nd instars, the dark grey ones are the 3rd instars and the black is the 4th instars. The largest adults are just giving birth a new baby. It takes about one week for the new born become an adults. From reference infromation, a female in general produce 100 nymphs in 30 days.
wpe5.jpg (40493 bytes) SCN_0001x.jpg (150864 bytes) SCN_0001z.jpg (161801 bytes) 
In the crowded colony, sometimes we can find a few winged adults. It is believed that when the colony becomes two crowded, some aphids will became winged and fly to a new location to start a new colony. In the above picture, there are two winged form adults and some other wingless adults. Also notice that there are three empty shells with a hole on each shell. They are the aphid body leave by parasitic wasp. 

Aphid Parasites Wasp

wpe12.jpg (47775 bytes)  
In the above first picture, there are three fat yellow-brown aphids, there are parasitised by the wasp. Notice the two on the upper side of the picture, are empty, the wasps had come out already. Near the two dark aphid adults, there is the white shell which is left from a ladybird larvae after moulting. 
SCN_0001z.jpg (161801 bytes) wpe15.jpg (49831 bytes) SCN_0002x.jpg (169934 bytes)
The above picture are taken at the same flower buds between one week. The first picture showing the flower buds are fully covered with aphids. But over half of the aphids population is yellow-brown in colour and fat, i.e., they are parasitised  by the wasp. The second picture, one week later, shows most of the yellow-brown aphids became an empty shell with a small open hole.

Ladybirds - the Predators

We found at least four different ladybird beetles attack the aphids at the same time. Both ladybirds larvae and adults feed on aphids.
wpe11.jpg (37545 bytes) wpe5.jpg (22231 bytes)
The first picture shows Variable Ladybird larvae. The second picture shows the Slimline Ladybird adult, beside feeding on the aphids, is looking for a place to lay eggs. Usually she will lay a batch of seven or eight eggs, on the bottom side of leaf. 
SCN_0006c.jpg (176341 bytes)  
Ladybird larvae feeding on aphids. The above pictures show the Yellow Shouldered Ladybird larvae and adult. 
The pictures show the Common Spotted Ladybirds Larvae and adult. We do not see any defence by the aphids against the predation. The aphids seem do not know or do not care about being eaten. They did not even border to run away from the attack. The only defence mechanism that we observed is their growing rate. To reproduce faster than the predation is their way of survival.
wpe20.jpg (43890 bytes) wpe19.jpg (51839 bytes)
The above pictures show some more different ladybird larvae and adult of Mealybug Ladybird.

Hoverfly - the aphids predator

wpe24.jpg (50489 bytes)
We often see bee-like flies hovering on our hibiscus plants. They are the Hoverflies. Hoverfly larvae are the major predator of the aphids. For a large aphid colony, we usually find a hoverfly larvae feeding at the middle. The 3rd picture above shows a Hoverfly adult look for a place to lay eggs.

Lacewings Larvae - the aphids predator

wpe6.jpg (17959 bytes)
We also found this Lacewing eggs and larvae on our hibiscus. Aphids are the major food source of Lacewing larvae.  

Tending by Ants

wpe28.jpg (69800 bytes)
Aphids excrete honeydew, which is a sweet liquid that is eagerly sought by ants. On the hibiscus plant, the ants are very active at night visiting the aphids colony. The ants come less frequently during the day time. This may indicate that the aphids give more honey-dew at night. 
Some ants species are known to provide some kind of protections to aphids. As we observed, the ants species shown did not provide any protection. They just wandering around and look for the honey-dew. They do not care the fly larvae or ladybird larvae eating the aphids.  

1. Insects of Australia - CSIRO, Division of Entomology, Melbourne University Press, 2nd Edition 1991, p 453.

Back to Top

Up ] Milkweed Aphid ] [ Cow Pea Aphid ] Rose Aphid ] Black Citrus Aphid ]


See us in our Home page. Download large pictures in our Wallpaper web page. Give us comments in our Guest Book, or send email to us. A great way to support us is to buy the CD from us.  
Last updated: October 09, 2010.