Kaelha; we could be Neighbors?
You say: "The property had an old Italian plum orchard and two very large old apples. The apples trees had been in place at least 60-70 years."
Over 20 years ago I inherited about the same thing ... If such trees aren't pruned regularly, they become monsters, big and 'leggy.' Storm damage will usually allow the introduction of rot and accompanying organisms; over time many an old apple tree will develop such hollow interiors. My favorite, and oldest, Gravenstein Apple tree has just such a cavity - in fact, a Douglas Squirrel is calling it home
! But as long as the balance between the root structure and the canopy remain, such holes seem merely a structural impediment, and the trees can live on for decades.
I've researched online a bit regarding the
Codling Moth life cycle and damage; I don't think they are responsible for your hollowed trees. Heres the site that described the following:
http://www.bugspray.com/article/codlingmoth.html {info on "CODLING MOTH CONTROL"}
[Codling Moth] "Eggs will hatch larva worms which will feed on apples; once they have gone through their growth they will leave the apple to spin a cocoon in which to change to an adult and then emerge to mate and reproduce."
---My guess (and experience) is much of that tunneling work was done by (our own)
Pacific Flathead Borer. I've got books that describe it pretty well, ...but here's some of what (little) I found online:
"Larvae are legless, cream to yellowish-white in colour, and have robust head capsules with well developed mandibles and a dorsal plate-like disc. The body is tapered and is half the width of the head capsule. From:
http://www.utoronto.ca/forest/termite/p ... m#Flathead"
---That's a fair description of the
ugly things; here's some more info:
The following is from:
http://www.attra.org/attra-pub/apple.html#insect [slightly edited]
"Another important production concern for organic or low-spray apple growers is borer control. There are two species of flatheaded borers that may invade apple trees. Chrysobothris femorata is the species endemic to the East. On the Pacific coast, C. mali fills a similar niche. Adults emerge from woodland trees in late April through early May, and begin laying eggs beneath bark scales on the tree. The graft union is a favorite place for egg deposition."
"Upon hatching, the larvae burrow under the bark and feed on the cambium—the layer of tissue just underneath the bark. Development is usually completed in one year, but sometimes two years are required. Maintaining trees in good vigor is important first-line protection from flatheaded borers, since a tree in good vigor will be able to drown an invading larva with sap. Drought-stressed trees are much more susceptible to borers; therefore, adequate water is essential." "...with the flatheaded borer, keeping the tree in good vigor is the first line of defense."
"Painting exposed burr knots with interior white latex paint is also helpful." "For all species of borers, the larvae can be removed from the trunk with a jackknife or piece of wire. Look for signs of borer damage, such as frass mixed with sawdust, at the base of the tree and at the pest's entry hole." "Perhaps the best non-chemical protection from all species of borers is to wrap the bottom 12-18 inches of the trunk in window screen (metal, fiberglass, or nylon are all effective). Secure the top with a twist-tie, being certain to loosen and re-tie at least once a year. The bottom should be snug against the ground or also secured with a twist-tie. Painting trunks with interior white latex also helps reduce borer attack."
- And this: "Pacific flathead borer: About 0.4 inch long with a dark bronze body and coppery spots on wing covers. Larva is light colored with a prominent flat enlargement just behind the head. Damage: Holes in trunk. Control: Paint trunk." --- From:
http://members.frys.com/~bpmosley/PESTS ... ad%20borer
--- I've lost young trees to these borers, and I assume they, along with carpenter ants, may be responsible for tunneling out the decaying interior of various damaged fruit trees. But there's no tree I 'wouldn't plant' for fear of their attack. For years I've painted my tree trunks with white (interior) latex paint - everyone loves the look! I figure if their first bite is a mouthful of latex, they might head back into the hills!
PS; I'm just south of Gaston, also in the "Coast Range foothills."