White Pine Weevil

From the Professor Tree Question Line

Hi,
My name is Silvia, I have planted Scot pines from PRFA for many years,
but the oldest ones 7 years old loose the top part of the tree.
The tree cracks at a certain height and the upper stem part falls.
In addition all the needles are yellow and the bark is not hard,
but like a film reddish that cracks peels.
The area also exudes sap, there is also a whitish substance.
The problem looks likeit starts from the trunk, and moves
outside toward the end of the branches.
The soil is very sandy and also very dry, and these past
two years have been very windy.
The trees were all in good shape at the beginning of the spring,
Are the  Scot pines trees could suffer from some disease.
Is there anything I can do? I appreciate any help and
advise you could give me.
Thank you so much.
Silvia C.
PS
I am very worried because it takes a lot for a tree to grow
here and now that these trees are big, they lose the top
part of trunk and branches. 

Sylvia,

Based on your description and the photos the problem is white pine weevil Pissodes strobi .

This native insect attacks Scots pine, white pine as well as white and Norway spruce. The damage is caused when the adults lay their eggs in the upper shoots of the effected tree. The larvae feed on the area under the bark known as the cambium. This feeding disrupts the flow of sap from the shoot and results in its death. The tree seldom dies from this damage and usually ends up with a misshaped top as a result. The damaged tops resemble a shepherd's crook this is a quick visual cue that the insect is present. Young trees are usually the target of this weevil. Removing the damaged crooks, by cutting them out a little below the damage, is an effective method of controlling these pests. The ideal time to do this is early to mid July around the time wild raspberries ripen. There are also chemical controls that are effective when combined with sanitation pruning.