Green Potato/Tomato Aphid

2022 December 4

This little aphid was riding on Sandy’s shirt when she came in from gardening on August 14, 2022. I wanted to get it on a better background for more visual contrast, but it was a surprisingly fast runner for an aphid, and it was about all I could do to track it with the camera and get a shot every now and then. This next picture shows it running across a magazine page. Those letters are typical magazine font, so you can see this is not a very big insect.

A little surprisingly, I think I actually have a positive species ID on this little tyke. It looks identical to the Potato Aphid (or, sometimes, Tomato Aphid), Macrosiphium euphorbiae. The body shape is identical, it has the same very long and thin legs with black feet, the antennae are much longer than its body, and it has the long, pale cornicles on the abdomen, with a fingerlike projection on the abdomen tip.

These aphids vary in color, probably depending on what they are eating. They range from green like this one, to gray, to a fairly strong red color.

As you might have guessed from the common name, these aphids are well-known for infesting potato and tomato plants. And, in fact, I expect Sandy probably picked this one up while picking cherry tomatoes from the two enormous tomato plants that we had at the time. But, those are not the only plants that they infest, oh no. According to the University of Hawaii:

The potato aphid attacks over 200 plants including vegetable and ornamental crops as well as weeds. Cultivated food hosts include apple, bean, broccoli, burdock (gobo), cabbage, celery, Chinese broccoli, Chinese cabbage, corn, eggplant, ground cherry, lettuce, mustard cabbage, papaya, pea, pepper, potato, strawberry, sunflower, sweetpotato, tomato, turnip, white mustard cabbage and zucchini. Ornamental hosts are aster, Easter lily, gladiolus, iris and rose. Weed hosts, such as lamb’s quarters, pig weed, ragweed, and shepherd’s-purse serve as important reservoir hosts for the species. – Univ. Hawaii

Part of the problem with aphids is direct feeding damage. They suck sap from plants, and if enough of them are feeding in one spot they can slow growth and cause new leaves and shoots to be deformed. But the bigger problem is that they act as a vector for a wide range of plant viruses, which can cause more damage to plants than simply feeding on them causes.

As is common with aphids, the wingless ones that you see in the summer are the females, which are capable of reproducing parthenogenically, basically cloning themselves. They can reproduce very fast this way, which is how you get masses of aphids suddenly appearing on your garden plants. But then in the autumn, they suddenly start producing winged males. These are still made parthenogenically, but apparently the females are triggered to produce eggs that have one less chromosome than usual, and these develop as males. The males then mate with the females, who go and lay eggs on their “winter host” plant (which, in the case of the Potato Aphids, is apparently plants in the rose family). They then hatch out as females in the spring, and once they are big enough spread out and find their summer host plants.

We generally don’t have really excessive aphid problems here, probably because our harsh winters keep them in check. I expect we also don’t have a lot of the viruses that aphids spread, because infected, weakened plants mostly don’t make it through the winter either.

One Response
  1. December 23, 2022

    They’re all female in the spring and summer, are they? Hmm. Well, next time I’m suffering an infestation and release a few jars of ladybugs, I’ll be sure to shout, “Take that, b****es!”

    Hmm. That probably wasn’t the kind of comment you were hoping to get, was it?

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