Grey caterpillar like bugs on Apple tree

[Papamunch]

Right now...I really need some help here please.
I have found a small greyish white caterpillar on my espalier apple tree. I have researched google and I think it is Apple Sawfly larvae. Does anyone know if that sounds right? If so what is the best way/stuff to use to get rid of it, and quickly. All I have been able to find on the www is something called Bifenthrin which also looks like it may have been banned from use. I normally use a homemade soapy solution spray to control nasty bugs etc and it usually works, well it does the trick on white fly anyway, does anyone know if it would work on sawfly larvae? I don't mind giving it a try but I also don't want to waste any time in getting rid of them because apparently they burrow into the core of the apples.

[FB.]

Since your tree evidently didn't have an attack last year, the caterpillar/grub must have come from somewhere else. Therefore, it may be something that you simply have to tolerate.

Apple sawfly larva tend to look rather like maggots; as do codling larva. They puncture a hole in the apple and tunnel out the core, pushing brownish excrement out of the hole. Sawfly larva are unlikely to be seen, other than occasionally having their head/tail briefly poking out of an apple when clearing out their faeces.

They do not attack leaves, unlike gooseberry sawfly.

Apple sawfly tend to only have one round of attacks each year. The apples usually have a noticeable track across the skin, looking like a big smile. The sawfly damage causes the fruit to drop early, but this can actually have a beneficial "thinning" effect on a heavy crop - allowing the remaining apples to grow larger. Sawfly-damage is relatively mild in comparison to codling.

Codling moth have multiple generations per year, which means greater amounts of damage. Like sawfly, they live inside the apple. A severe codling attack can destroy the entire apple crop (although I once posted a "how-to" for salvaging a lot from a maggot-damaged apple). Some apple varieties are very prone to codling (or sawfly) attack, while others are somewhat resistant. Some years are worse than others. Warm, mild and dry weather allows them to multiply rapidly. Cool, wet and windy weather can seriosuly disrupt their reproductive and growth cycle.

On a mature bush/tree, sawfly is not generally a serious enough problem to need dealing with. However, codling can be very serious.
It is possible to use insecticides, but you run the risk of contaminating yourself or children - and the risk of residues in the fruit when you eat it. You will also kill useful predators, such as earwigs, lacewings, ladybirds etc, which have been known to eat many fruit tree pests. Earwigs in particular are thought to be very fond of eating codling and sawfly eggs.

Many people use "pheromone" traps for codling, while others use home-made traps similar to the wasp-trapping jam-jar method (but instead containing some cider, water, sugar and crushed apple). A whitish sheet of sticky paper is used for sawfly, with sawfly being attracted to a certain ultra-violet-reflecting shade of near-white (presumably somewhat resembling the light-reflection properties of the whitish flower petals onto which sawfly lay their eggs).
If you use chemical sprays, you will need to apply several doses of insecticide during the course of a season, to be sure of blocking all pest attacks.
But ask yourself: is spraying worthwhile on a young tree, given the cost of pesticide, the health risks and the small crop on a young tree which will probably be eaten by birds even if the grubs don't get them first?

But....having said all the above, I suspect that you have simply found a leaf-munching caterpillar that is unlikely to do more than munch a few holes in the leaves before a smart bird sees the damaged leaves and knows that a big juicy caterpillar often hides under leaves with holes (even sparrows soon learn that curly leaves contain aphids and ants, both of which sparrows will eat).
If the birds - or even wasps - don't take the caterpillars but they're causing a major problem, pick them off and squash them.

If your fruit is not being damaged and if there is only minor leaf damage, I would not worry about it.

[Papamunch]

Thanks for this FB. The tree is new, I only planted last Autumn so I have no history of previous attacks. I have picked the grubs off and squashed them all. I have also given the tree a soapy wash, not wanting to use chemicals really and so far there appears to be no return of the little offender. Your reply is very informative and appreciated.