About the aphid
Corn leaf aphid, Rhopalosiphum maidis, is a globally distributed pest of grains including maize, sugarcane, millet, sorgum, and barley (seen here). Rhopalosiphum maidis will stay on these grain hosts all year in many warmer locations, but in places with colder winters may either move to woody hosts in the genus Prunus or, more typically, simply reinvade every spring from warmer locations. Females typically give birth to more females year-round and males are rarely recorded, making it what entomologists call ‘anholocyclic’ (without a complete lifecycle) in most locations. These aphids are an interesting almost blue-green color, with darker areas around the head, thorax, legs and cornicles that become more pronounced in adults. Besides feeding damage, R. maidis can transmit several plant viruses and also produce substantial buildups of sticky honeydew which may can foster the growth of surface fungi.
About the photos
I ended up getting quite a few shots of R. maidis that I am satisfied with, and got good representation of winged and wingless adults as well as many stages of nymphs. I am finding that, for the most part, I have more luck getting interesting shots with aphids on stems and narrow leaves of grasses than broad leaves. A narrow leaf or stem allows me to shoot the aphids from a greater variety of angles. When aphids are along a leaf margin, I can even get some nice side-profile shots that make mouthparts, eyes, and leg attachments easier to see. The parallel veins of grasses like barley can also add a nice texture.
In several of the shots, cast skins (exuviae) of molting aphids are visible. These white or grey exuviae are sometimes confused with either live or dead whole aphids, but are simply an indicator that aphids are or were recently present. Most if not all aphids (I cannot remember if there are exceptions right now) molt four times between birth and adulthood, so often there are as many or more of these cast skins on infested plants as there are live aphids.
About the aphid
Well, after quite a period of neglect, here are some new aphid photos . . .
Uroleucon sonchi is appropriately called the Large Sowthistle Aphid, as it is both large and found on plants in the genus Sonchus, or sowthistles. The individuals shown here are quite red, especially the juveniles, but they are often darker brown in color as well. Adults are very large, with long antennae and legs with darkened joints. Their size and morphology make their mouthparts quite easily visible compared to some of the other aphids. No winged morphs are pictured here as there were none in the colony at the time, but they do occur, especially when crowded. Most aphids in the genus Uroleucon are similarly sized and colored, and colonies are often easy to spot in the field. This species can be found both on stems and the undersides of leaves.
About the photos
The large bodies and long apendanges of U. sonchi actually made them a bit trickier to photograph than some of the smaller aphids for two reasons. First, I had to be careful to ensure that legs or antennae would not be cut out of the frame, and second, my narrow depth of field made it nearly impossible to get a whole aphid in focus and even harder to focus on more than one. For example, the photos below show three different views of the same three aphids. They made a nice little grouping of three different developmental stages, but I could never get more than two in focus unless I shot from directly above which makes for a much less interesting view.
Since these aphids were mostly on Sonchus leaves (and pretty ones at that) instead of stems, I couldn’t get any of the black background shots like for S. avenue before without destroying the plant. One neat thing about a couple of the above photos however is the presence of water droplets due to high humidity inside the cage. I think they make a nice touch and wish there were even more.
MC Kaiser Blog
Photographs of aphids by an enthusiastic amateur.
Images free for educational use with attribution.
Please contact me for any other uses, or visit my portfolios at Shutterstock and Dreamstime
First post and introduction here
If you are trying to identify live aphids from pictures, I highly recommend the website InfluentialPoints.com
For ID keys and a quite comprehensive catalog of aphids and their host plants see Aphids on the World's Plants
There is always the chance of one of our colonies getting contaminated and me posting a misidentified aphid. These images therefore should not be used to make formal identifications.
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