What is this insect on my Flame grapefruit?

Last night I was checking out my trees and noticed what at first looked like bird droppings on the leaves of my grapefruit tree. Upon further inspection they appear to be an insect of some sort. I was able to flick them off easily enough, any idea what these are?

Looks like a slug of some kind to me.

that’s what I thought as well. makes sense considering the slime trails visible on some of the leaves…easy enough to remove by hand, just trying to figure out if they’re harmful.

Swallow tail larvae. There big eaters but they go away. The trails could be citrus leaf miner.

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Wildscaper nailed it. Citrus leaves are fodder for the giant swallowtail larvae, which are disguised as bird droppings. They lay eggs, which are tiny orange dots, singly on leaves. Sometimes the upper side and sometimes the lower.

If the tree is large enough, the larvae can be left to munch away without lasting harm to the tree. Caterpillars have quite an appetite before they reach the stage of becoming a chrysalis, though. So, they should be removed from small trees. The giant swallowtail, as its name indicates, is a very large butterfly.

Also, the paths along with the curled edges on those leaves do appear to be the work of leaf miners. Leaf damage from those is usually more cosmetic than harmful.


Yes, there is more than one swallowtail caterpillar species that looks like bird droppings, Giant Swallowtail is best known.

Here’s Western Giant Swallowtail laying eggs on my CaraCara navel orange.

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Yep, I see those guys fluttering around the garden all the time. Worth it to allow a few munched leaves to see such a stunning butterfly.

good to know it’s swallowtail larvae. I’ve seen them around the garden quite a bit. I’ll just leave them alone.

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over the weekend we were sitting at the table eating lunch when my oldest daughter said “daddy, I just saw a giant swallowtail”…funny part was I hadn’t mentioned anything about the larvae so she was just observing…anyway, I went out into the yard and sure enough it was over by the orange tree. Big one too.


Jeremy, I’ve twisted wire near where they layed eggs. Too hard to remember where they are, maybe get a series of development pictures.