Lemon Tree - In Mortal Danger?
August 6, 2016 12:02 AM   Subscribe

My lemon tree is under attack. Leave are mysteriously nibbled, and I'm scared.

For the past three days, something has been attacking the fresh leaves of my lemon tree. This is very frustrating, as it was just getting better after an attack of scale. It started around the time of a large rainfall (it's in a pot out on my deck), when I noticed one small shoot that had a frayed end on it. I thought it was just a one-off thing, but this morning I found several leaves that looked like they had been eaten, some right down to the central vein: http://imgur.com/PNTbtZx. What's worse is that one of the two lemons has been ruined, gnawed to the sweet treasure therein: http://imgur.com/o2IJKgQ

I have been looking for the culprit. First thing I found was this one beetle: http://imgur.com/aG98jNS. Then I found about ten of these small caterpillar-like things, and thought they were the likely culprit: http://imgur.com/aKJuJFI. I removed all I found around 8pm, four hours ago.

Then just now, I went back to find four more leaves eaten (detail of one: http://imgur.com/34eDU89). I looked and found one more of those caterpillars, but also several (a group of about six) very small black ants in the soil of the pot. Could those be doing this too? Is my dear plant getting ganged up on by a Red Dawn of herbivorous jerks?
posted by smasuch to Home & Garden (7 answers total)
First of all, your potted soil needs help. If the soil was healthy, your tree would not be under siege. There are DIY and commercial fertilizers and soil enhancers - Google, go to your best local garden center and ask advice. You can also buy soil test kits for $25 to $30. So that's longterm.

Short term, spray the tree with a mix of water, canola oil, and ivory liquid soap (I think Castile Soap is great, too.) Recipe here. That will kill or deter current threats.

It'll be fine.
posted by jbenben at 12:18 AM on August 6, 2016

Best answer: Squirrel. They eat the rind and leave the fruit and eat tender leaves sometimes too.
posted by fshgrl at 1:35 AM on August 6, 2016 [2 favorites]

Response by poster: I put it inside last night, and no nibbled leaves are there this morning. I'm leaning towards a squirrel indeed being the culprit, @fshgirl.
posted by smasuch at 9:22 AM on August 6, 2016

The first culprit to look at with night time leaf damage in the PNW is slugs and snails, which are very good at hiding themselves during the day. But I agree the damage looks more like squirrels.

Incidentally, the beetle you found looks like a ladybug, which are predator insects and are protecting your tree. I can't be sure from the picture you posted but I kind of suspect the caterpillar-like things were ladybug larvae (also predators).
posted by emyd at 9:45 AM on August 6, 2016

Seconding that the larvae is a juvenile ladybird and the beetle is an adult ladybird. They are your friends! Free pest control, though obviously not of the relevant pest this time.

I'm not sure about the leaves/lemons. I thought ants when i saw the cut patterns though.
posted by intergalacticvelvet at 1:25 PM on August 6, 2016

Best answer: Yep, those "caterpillars" are larvae of lady beetles, good to have around. The damage looks like earwig damage to me, but the rind gnawing seems like it could be snails or slugs as well. Both earwigs and snails are active at night.

BTW, fertilization is often an attractant to pests and pathogens, especially high nitrogen fertilizers. Potted plants should be fertilized at low rates during the growing season, with appropriate fertilizers. Fertilizer should not be used as a general "cure-all", and adding fertilizer to soil with the wrong pH won't do any good because the plant won't be able to take it up.
posted by oneirodynia at 2:46 PM on August 6, 2016 [2 favorites]

Response by poster: I haven't seen any slime trails on the deck from snails/slugs. There are some larger ants that are out on the deck sometime and have been on the tree before, but I never noticed anything like this before when they were present. I think they were mainly after the sap via the scales.

I didn't realize that bug as a ladybug without the bright red shell. Sorry, larvae.
posted by smasuch at 4:34 PM on August 6, 2016

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