Lacewings

Amy:

Thanks for the gift of the lacewings.  I released them recently by sprinkling the larvae in several different areas of my garden.  I'll report back on how they are doing periodically.  In the mean time, here are a couple of pictures, including the instructions that accompanied the lacewings. 

Broccoli Leaves and Aphid Poop

Amy,

Creatures are feasting on the leaves of my romanesco broccoli. The good news is: they left the gorgeous purple broccoli head untouched, and I'm probably going to eat it soon anyway, so no worries. This is the last of my romanescoes this year. I started with six plants, and the other five all matured much earlier this spring. They are delicious - very delicate flavor when steamed and served with butter and salt and pepper. For some reason, this one lonely broccoli took much longer to mature than the other 5. None of my broccoli plants showed any pest damage until now.

I peeked under the leaves and found some aphids (see below). But the aphid population isn't all that large. The picture shows one of the largest clusters that I found. Are the aphids causing the main damage, or is it something else? I would like to know for future reference and also to assess whether the problem might spread to my other veggies nearby, which include swiss chard, leeks, carrots, tomatoes, green beens, and squashes.

Rachel,

So, the good news is that the aphids aren't really a problem. I mean, get them off of there before the population explodes. If you have a few warm days, that little colony could overtake the garden. Seriously. Females can reproduce asexually. Each adult female can produce up to 80 offspring in one week. Each of those 80 offspring then produce 80 of their own, who produce 80 more. That brings us from 1 female up to 512,000 aphids in less than three weeks. Anyway, wipe them off. I assume you already have, but it bears repeating. Do this even though you're about to harvest the broccoli, cause they'll just create some winged forms, pop out a few males, and fly over to your tomatoes to start all over again.

Aphids don't take bites. They have piercing sucking mouthparts. It's like a straw. They insert this straw into the leaf and look for a vein full of phloem. This is the sugar/sap and basic life-blood of the plant. They drink a lot of this. Actually, they drink enough to poop out some stuff that is basically sugar. We call this honeydew. There's a lot of evidence suggesting that the manna the Israelites ate was Honeydew from a particular kind of insect. It's pretty sweet, and not at all poopy tasting. (and I probably shouldn't admit that I know that, but, whatever). Ants will eat it. Ants will actually farm honeydew producing insects, protecting them from natural enemies. So, while ants are not pests, they're a pretty good indication of a problem if you find them all over a plant. Anyway, you can see how the leaf has turned yellowish underneath the aphids. That's typical aphid damage.

About the bites. Are you sure that's not slug damage? I'm less familiar with slug damage. I always look for slimy trails, because I can never remember the size of their bites. Those don't look like smooth margins. You have a lot more experience with slugs than me, so I'll defer. I'm curious about your slug program, though. Have you ever used beer traps? Copper barriers? I've heard inverted melons work really well too.

If it isn't a slug, then it's probably some type of caterpillar. These things are voracious. Since you'll be harvesting soon, let's focus on preventative measures. Look for caterpillars in the early evening or late morning. A little Bt wouldn't hurt, just as a preventative for your nearby plants. I'd suggest that you at least remove all of the leaves right after harvesting. It might be a good idea to remove the plant and turn the soil.

Black Bug on Tomato Plant

Amy:

I have never had a problem with pests on my tomatoes until this spring. Some of the tomato leaves have bites taken out of them. Luckily, the recent hot weather and sun have given my tomatoes enough vigor to ward off the effects, but I took a couple of pictures a few weeks ago when I was concerned about them. You can see it in the first picture, below.

I noticed a little black bug on some of the leaves. I used the macro setting on the camera to take a close-up of it. Thoughts?

Like I said, the good news is that most of my tomato plants are tolerating whatever pest it is. It's not killing them completely. But I'd like to know what it is, because it's certainly taking out some of the leaves, which are very important for sugar production to fuel the tomato fruits that will arrive soon.

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Rachel:


I... really don't know what the black bug is. My first thought is that it's some sort of robberfly, which would be good. However, the wing placement is wrong. And it might be a leaf miner you caught while ovipositing. A taxonomist would be able to look at it and say, "Oh, that's a grylloblattid." (Actually, a taxonomist would never say that because grylloblattids live under glaciers, but you get my drift.) Keep an eye on the plant, and let me know if you find any more. If you do, try to get another picture. I should warn you, though, that I'm better at identifying larval stages that are more likely to be eating the plant. Most of the adult pests of tomato (ie insects that eat the leaves when they are fully grown) are beetles. If this is a pest, it's probably a female depositing her youngsters.

I'm more concerned with the tiny green things I can see below that gal. I can't tell what they are from the picture. If you could go out with a magnifying glass or loop and describe them, that would help. They could be psyllids, which are only a few millimeters long, but you said the tomatoes are doing well. Psyllids have toxic saliva, which causes the leaves to turn yellow. They probably aren't causing the holes. So, even if you have a few psyllids, the plant is overcoming them. They could also be little baby leaf miners that the mom just popped out. I really don't know.

Whatever it is, it can cause the plant to produce less fruit.

Let's talk damage: you've got a moth leaf miner, but it doesn't seem too bad from the picture. You've got something taking out large holes. Normally, I'd assume this is some kind of worm (caterpillar), probably a cabbage looper and maybe a hornworm. Cabbage loopers (see left) are small, green and cute. They hang out on the underside of leaves, and chew everything but the leaf stems. Hornworms are big, with a horn sticking out of their butts (see left below). 1 lonely hornworm can do a lot of damage to a given plant, but Home gardens don't usually have more than one or two. These caterpillar eggs are laid singly, and the insects have a relatively large generation interval. If you don't have a heavy infestation, just pick any caterpillars off when you find them. I'd hate to waste any Bt on a plant that's doing okay, because it may be something else. But check the plant. Hornworms will eat your baby tomatoes too. Make sure you check the plant when there is plenty of daylight, but the sun isn't directly shining on it. Early evening and late morning are good times to look.



There are a number of beetles that feed on tomato leaves. The small things I can't see could be flea beetles. They leave smallish holes in leaves, some of them expanding to create bigger holes. You'll see them hanging out all over if it isn't too hot out. Let me know if you find any beetles on the plant. If you find one that looks like the picture on the right, don't touch it. It might have color on it, but the body style will be similar. That's a blister beetle. They cause, wait for it... blisters! I don't think you have any of them. If you find some, let me know. We'll talk pest management then.

Finally, there are leaf miners that can cause holes to appear in a plant as well. I see some "windowing" damage, where all of the leaf is removed save for a thin layer. Sometimes these thin layers get knocked out (by watering, wind, etc) and turn it into a full-fledged hole.

Do me a favor and look closely at the holes. Does it look like they were formed by something taking small bites, and turning it into a big hole? Are the edges pretty rounded?

Look for caterpillars around your tomato plants; look for any kind of beetle as well. If you can find any of the things I circled in the first picture, try to get a better look at them. Also, if you can get another picture of the black fly-type insect. If the damage has changed at all, I'd like to see another big picture of the plant.

Also, I realize this is a little late. So if your tomatoes are doing fine, then just ignore!

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Aim,

You are a major dork. What is oviposting?? It sounds like a scientific euphemism for bug sex.

Speaking of which, the black bugs are multiplying. I examined another tomato plant this evening and found a community of the black bugs. I took some more pictures (see below). Damage-wise, the only thing I can find is some mysterious curling of the leaves. At first I though the curling had to do with lack of water, but no. So, I can't tell if the black bugs are good-guys eating something bad that I cannot see, or whether they are chomping on my tomato leaves, or whether they are just chilling and keeping it real.

But it's a little unnerving to see the congregation of them on my tomato. I'm obsessed with my tomatoes. It's hard not to be obsessed with tomatoes in the pacific northwest, where tomatoes arguably are not supposed to grow, because it is so far away from their native climate. I start them from seed in the late winter and nurture them all the way through the clouds and rain of spring.  I get very invested in seeing them eventually produce fruit.

Anyhow, here are the mystery bugs.

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Rach,

Ovipositing is totally all about sex. Sorta. The sex has already taken place. It refers to when the female deposits a fertilized egg. And it covers all kinds of activities. A leaf miner, for instance, has a structure which slices into the leaf but not all the way through. Therefore, when the egg hatches, the larva is protected inside the leaf. Honeybees have converted their ovipositors to stingers. So a male bee can't sting you, because they don't have the sexual organs to create a stinger. Dragon and damselflies have long ovipositors because they place eggs on vegetation just below the surface of the water. You'll see the male riding piggyback on the female, until she dips her abdomen into the water. He's making sure that another male doesn't eject his sperm and replace it with his own. Some males get around this by pretending to be females. So the other guys don't know that she mated. We call these "sneaky males." Highly scientific term, there. Also, if the female has mated twice, she can manipulate which sperm she prefers while it's all mixing around in her spermatheca (doesn't that sound dirty). Insects have some pretty freaky sex. That's actually pretty tame. Don't get me started on spit balls.... Anyway. uh. So that's ovipositing.

I'm a little confused because I don't see any damage on the leaves. Is there any substantial damage? This morning I was thinking it might be leaf miners. But I don't see any mining going on in these pictures. I'm actually leaning towards psyllids again. They certainly look like psyllids from here. Also, the immatures are so small, they can be hard to see. They cause the most damage in young plants and transplants. They also cause curling of the leaves. Here's a picture of an adult psyllid.

I think I mentioned this earlier, but psyllids introduce a toxin that causes leaves to turn yellow. We don't know think the adults do this. It's possible that you had a pretty large population of immature psyllids bothering the plant, but that the adults are now hatching. They're still feeding, but they don't have toxic saliva. That might explain why the plant doesn't seem as stressed. Of course, these psyllids will reproduce. You might go through another cycle where the immatures damage the plant. It might be strong enough to overcome them at this point. I'd say just keep an eye on it. Maybe wipe off the plant and try to kill as many as you can. If the plant starts looking bad again, there are organic pesticide which seem to work okay. There are natural enemies of psyllids, like the lacewings you're releasing, but they don't seem to eat the psyllids during the time they're dangerous. So, organic pesticides work in a pinch. Specifically the Ensure version of Spinosad. This is a nicotine-based pesticide that's made from fermenting the microorganism Actinomycetes spinosa. It targets the nerve synapses by binding to the nicotine receptor site. (There are some nicotine-based pesticides that are NOT organic, just FYI). It doesn't harm natural enemies. It comes as a spray, so you don't have to worry about eating it. Just clean off the tomatoes, if you spray when you have any.

Oooo also. If you know you have psyllids in the garden, DON"T use any carbamate pesticides on any other plants. Sevin is a common name. They actually promote psyllid populations.

Purple Coneflower

Rachel's Question

Something is wrong with my purple coneflower. All the sepals around the bud are curling and looking mangy. Upon a closer examination, I noticed that there was a very small centipede-looking creature - see the far left-hand side of the second photo. Additionally, there are a lot of very, very tiny white dots. You can barely see them in this photo. Are these two separate pests or are they related somehow?

Amy's Answer

The "centipede" thing is good. It's an immature lacewing, and it's eating the bad things. Lacewings are seriously bad-ass. They're also very pretty. So don't disrupt anything that looks similar to these pics.

The dots are pest eggs. Wipe them off with a damp cloth. I see some immature leaf hoppers on the plant. I've circled them in the picture. This is kinda bad, actually.

Leaf Hoppers are piercing/sucking feeders that feed on the phloem of the plant (much like aphids, but not as easily removed as slow, clunky aphids). They're hard to treat with a surface deterrent, because they eat the sugary syrup inside the plant. Unlike aphids, they also produce more winged adults, so they can just come back after you clean them off. Do it anyway, though. Look for the rounded little green things and GET THEM OFF. Also the dots.

So, here's the really bad news. Leaf Hoppers transmit Yellows disease to Purple Cone Flowers. Yellows disease is caused by a phytoplasma that reproduces in living plant tissue. It causes, well, yellow leaves, stunted growth, and sometimes a reddish tinge to the leaves. The flowers produced will be sterile, and organs and shoots will be deformed. I don't know if your plant has it, and the only way to tell would be to look for characteristic structures in living plant cells under an electron microscope. I'm assuming you don't have one of those sitting around the house. Also, I wouldn't even be able to tell you what to look for. This wouldn't be such a big deal except that those filthy little (even though they're cute) leaf hoppers will spread the disease to anything else they taste in your garden. Things that are affected by Yellows Disease - in addition to echinacea - include: monarda, caraway, marigold, snapdragon, aster, mum, daisy, carnation, strawflower, carrot, broccoli, tomato, radish, squash, ragweed, thistle, plantain, and dandelion. So you really don't want it in your garden.

There is no cure for Yellows Disease, other than removing the plant. Now, we don't know for sure that you have it. All of this damage could be caused by the leaf hoppers. They like to eat flowers first. If you're really worried, you could sacrifice the plant right away. First, though, I'd like to see if the plant gets better if we treat the leaf hoppers. Try removing as many as you can. Go crazy on the dandelions in your yard, just in case. Check your other plants for leaf hoppers, as well. And watch any new growth on the plant. If you can't see anymore leaf hoppers, and the new growth is still wonky, then you'll need remove the plant.

There are some systemic pesticides out there that minimize harm to other insects - you pour it into the ground and it only affects insects that feed on the phloem. But they aren't organic. Some are nicotine-based and pretty selective in damage due to the type of receptor they attack. The FDA assures us that they aren't harmful to humans. They're probably correct in that, but there is some data indicating that they might be harmful to bees. I only mention this in case it becomes clear you have Yellows Disease and you need to save the garden by killing all of the infected leaf hoppers. This is worst case scenario, and pretty unlikely. Just an FYI.

Meanwhile, I'm going to look for some IPM methods to deal with leaf hoppers. We'll see how the plant does and move on from there."