Unidentified pest

[Pennypuff]

I noticed some of the leaves on my Chinese Elm turning yellow then brown and falling off a few days ago. At first I couldn't see what was causing it, and thought it might just be the cooler weather, but this afternoon I had a closer look and noticed black spots on the underside of the leaves. After much neck straining and squinting I discovered these white grubs (see pictures hopefully uploaded below) under many of the leaves.

I am extremely new to bonsai and gardening in general (the bonsais are saplings from a bonsai nursery and potted a few months ago). Can anyone tell me what these grubs are, will they kill the tree (there are three in a landscape and all appear affected) and how can I safely get rid of them? I should mention that they are kept indoors, but on a bench near an open window with plenty of ventilation, lots of natural light and I water them every second day and mist them with water in-between. I live in an apartment, however I am prepared to put them outside in the communal garden if necessary for their survival.

Really appreciate any help!

[Paulneill]

Hi

I picture of the tree may help . I saw pests like this just yesterday while cutting some trees in the garden .
I wouldn't have thought they would make leaves go brown and fall . You said you repotted the trees a few months ago did you root prune at the wrong time of year ? Maybe over watering ? Weak trees are more prone to pests. What type of soil do u use ?

Paul

[shibui]

Pics are not really clear enough but the bugs look like aphids but I can't make out any legs. Pyrethrum is relatively low toxicity and safe enough to use indoors and should kill aphids and most other bugs. pyrethrum is a contact pesticide so you have to spray every part of the plant and will probably have to spray several times a week or 2 apart to get any new ones and the ones you missed first time.

Must say that i do not think Chinese elm will stay healthy inside for very long.

[Pennypuff]

Hi Paul,

As I mentioned, I am very new to this. I don't know what potting mix was used, the roots were trimmed a little but not as much as you would normally trim.. less than 1 third taken off? They were potted in january, and have looked healthy with plenty of new leaves shoots etc. until now.

I have noticed the occasional winged bug running around on the trees (didn't seem to fly very much), but didn't worry too much about it, Im wondering if these grubs are perhaps the larvae of this bug?

I've uploaded a couple more pics of the trees, not great quality though.

Thanks for your help!

Maxine

[Pennypuff]

Thanks for the tip Shibui!

I'll try the Pyrethrum tomorrow. I've already been warned of the dangers of keeping a bonsai indoors, but sadly I don't have a private outdoors to keep it in. Wanted a bonsai to bring a little greenery back into my life! But I will definitely get it outside if I notice it struggling!

[Bradeen]

Agree with you guys these but i think you should see some signs of these pests and this is also helpful for the treatment of these pest. These signs are helpful to the better treatment of these pests. For this purpose you get the the services of expert also which is good step for the removal of these pests.