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Monday, June 06, 2011

Tomato Worminess

We have a lovely and promising bunch of tomato plants this year.  One day I noticed this green caterpillar and the hole it had eaten into a succulent tomato leaf.  Alas, there are numerous green or greenish caterpillars that will feed on tomatoes, from info found at California Integrated Pest management site and an assist from

Heliothis zea; usually known as corn earworm but called tomato fruitworm when it's damaging tomato crops.  Not this one; H. zea tunnels into the tomato fruits instead of eating the leaves.
Beet armyworm, Spodoptera exigua feeds on leaves of tomato; however the eggs are laid in a mass, the caterpillars feed as a group, skeletonizing the leaves.  So that is not a likely suspect this time.
However, two species called "tomato looper" (again multiple common names to match the crop under attack) are likely to be my tomato worm:  Autographa californica (Alfalfa looper) feeds on about 50 different plants especially legumes like alfalfa and clover.  Trichoplusia ni (cabbage looper) larvae feed on plants in the cabbage family and "many other garden plants".  My caterpillar looks a bit more like the cabbage looper; and in the photo I think you can barely tell there are just two pairs of abdominal prolegs, confirming looper status.

And then there is the tomato hornworm we all know and love (not).  This one just hatched and so is very small (about .5 cm long) but of course had the potential to grow to about 3 inches and wreak havoc among the tomatoes along the way.  But is this really tomato hornworm (Manduca sexta) or is it M. quinquemaculata (tobacco hornworm)?  The two caterpillars can be told apart by the markings (backslashes on tomato, Vs on tobacco).  Anyway, here is a photo of an egg of one or the other hornworm.

I'll never know which hornworm that was since Mr. Cardui has rid our tomato crop of caterpillars of all stripes and markings by applying DiPel, a bacterial insecticide that works well on lepidopteran larvae.  Sorry, that cute little hornworm was probably already sick when I took the photo.  Can't risk holes in the tomatoes now, can we?


Cindy said...

Hey, just this morning I was checking my tomato plants and I found what I think are hornworm eggs. I picked off most of them, left one on the plant and put one in a jar to (hopefully) raise.

And, take a look at this great series of super-duper macro shots of hornworm egg and caterpillar that I found recently.

Christine said...

Autographa? Perhaps named because it likes to leave its mark? What I'm wondering, however is how in the world you've managed to already have tomatoes on your plants and I have pathetic sticks in the ground?! So jealous!

vanessa cardui said...

Wow Cindy those pictures are amazing; you can see the little guy all curled up inside the egg.

Christine, I give 60% of the credit for the tomato success to my husband, Mr. Cardui and 40% credit to the amazing mild weather we're having. It helps to be able to plant early (way back in March).