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It's not as massive as it might seem on this picture. The insect is about 1 to 2 mm in length. The web is very fine, you don't see it if you're standing a meter away and only the upper shoots are affected.

It's located in North-Rhine Westphalia, Germany, has direct sun and its neighbours are sage and lavender. They have no signs of infection. Will it hurt them?

What are those insects on my rosemary and how do I make them go away? Macro shot of the pest

A picture of the plaque. The brownish thing is not related to the pest: enter image description here

I'm sorry for the low quality. This is one of those insects. They currently reside on the underneath of nearly every leave. enter image description here

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  • Is this plant indoors or in a greenhouse?
    – Bamboo
    May 29, 2016 at 9:09
  • It's on the window sill outside. It's protected against rain because it's underneath a balkony.
    – bot47
    May 29, 2016 at 10:55

5 Answers 5

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This looks like cat or dog hair and an immature flea. What is wrong with your rosemary other than these fine hairs/webs? There will always be all kinds of insects on your plants but what was it that drove you to look so closely. Maybe this should be a comment not an answer I guess. I'd just take a hose and with a firm stream hose your rosemary off.

Webs would rarely have 'loose ends'. They would also bend with weight and age. The main problem is how your rosemary has been damaged? Please send more pictures and details. This picture is absolutely gorgeous and I am not at all sure about a flea! There are so many insects out there and MOST of them are beneficial! Very, very few insects are a problem to our gardens!!

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7
  • This certainly can't be hair of any kind as it located on a window sill. What can't be seen on this photo is that the rosemary got white spots on its leaves. Also the white plaque on the stalk doen't look right...
    – bot47
    May 28, 2016 at 19:39
  • I added more pictures of the plaque and the insect.
    – bot47
    May 29, 2016 at 16:31
  • What super pictures! I've got to go do a bit of research but MEALY BUG might be part of this...you might have a few problems not just one. My goodness what beautiful pictures! We've got to add to our picture-taking suggestions to add something for scale...thanks for the additional info!
    – stormy
    May 30, 2016 at 18:02
  • Aphids, spider mite, mealy bug, powdery mildew...? I'd take that plant and give it a good shower. In addition, I'd take your plant out, clean the pot and then add new potting soil. I would do this with all of the plants on the sill. A good shower, and I mean put them in your shower, turn the water on (cold) and drench your plants. Allow them to drain well and put them back on your sill. Make sure your saucers are dumped out! Do not water again until the soil is dry. I would then do the shower once again. All of these little problems are due to dryness in their environment.
    – stormy
    May 30, 2016 at 18:14
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    Well shoot, I missed the window sill OUTSIDE. Still holds except you can use the hose. Plants under a roof are as susceptible to powdery mildew, aphids...because they don't get washed down.
    – stormy
    May 30, 2016 at 18:21
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It appears to be an aphid

Many immature insects have a common look and identifying them can be challenging.

This particular pest appears to be an aphid. The strands 'silk' are also a telltale sign of aphids.

enter image description here

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4
  • I'd expect it to be covered in aphids. Not just the one.
    – Graham Chiu
    May 29, 2016 at 7:26
  • I added another photo, I don't think they are aphids.
    – bot47
    May 29, 2016 at 16:30
  • Do a search for wooly aphids. The pictures you'll find look very much like the second photo you posted.
    – OrganicLawnDIY
    May 30, 2016 at 13:00
  • OP, keep in mind that aphids come in many colors. These are the colors I've personally seen: reddish-brown, green, yellow-green, yellow, black.
    – Bulrush
    May 31, 2016 at 11:06
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As of now, some of those larvae evolved and they really look like thrips. Also, the picture of the larva I posted in the question looks really similar: enter image description here

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2

I can't help but conclude this is one of the spider mites - there are certainly tan coloured mites, but what's odd is, rosemary oil is often used as a treatment to get rid of them. Even so, there are mites that will infest Rosemary, but I've never seen this in colder parts of Europe, they're usually indoors or in hotter countries, so I'm wondering whether the very sheltered situation the Rosemary occupies, along with direct sun, has enabled them to infest the plant and survive outdoors.

I would treat with Neem oil, since you can't just use any pesticide because its an edible plant, and that will deal with most insects anyway, including scale, although I wouldn't expect webbing with scale infestation. More info here, but its an American link, because that's one of the countries that does have plenty of spider mites living outdoors

http://gardening.yardener.com/Problems-Of-Rosemary

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  • I tend to think it a spider mite, but mine has a pointed end, while most pictures show them round.
    – bot47
    May 31, 2016 at 20:16
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It looks as though there is some fuzzy white stuff over the stems like powdery mildew which is common in household rosemary plants. This leads to secondary attack and webs are a common sign of spider mites. The insect pictured might just be another opportunistic passerby.

Now that you've said they're all over the underside of the leaves, I'd spray the plant with pyrethrum to eradicate them. There's a holding period, but check the bottle.

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