Insect identification > Coleoptera > True Coleoptera > Flat-headed apple tree borer

Flat-headed apple tree borer


Flat-headed apple tree borer (Chrysobothris femorata Oliv.). This is probably the most injurious of the buprestids. It attacks more than 30 kinds of trees and shrubs, generally selecting individuals which are not in a healthy condition or are otherwise favorable for their larvae.

The beetle is about half an inch long, rather broad, dark brown, faintly marked with bands and indefinite spots of gray, and having a brassy metallic reflection at certain angles. The underside is bronze, and under the wings the abdomen is a metallic greenish blue. It occurs almost everywhere in the United States and in Southern Canada and is a serious enemy of fruit trees.

The beetles appear soon after apple-blossom time and live for several weeks. They frequent the sunny side of the trunks and limbs of trees. Here the eggs are laid in fine cracks or under small scales of the bark. They hatch in from 2 to 3 weeks and the tiny larva bores into the inner bark, feeding on this and on the sapwood, and grows rapidly unless the tree is vigorous, in which case such an outpouring of sap may occur at the wound as to kill (drown?) the larva or drive it into the outer layers of bark where it may live for a time, later working back into the sapwood if the flow becomes small enough to permit it.

If the larva can feed in the sapwood, it will grow to full size, about an inch long, by fall, at this time burrowing into the wood to form a pupal cavity in which the winter is spent, pupation itself taking place there the following spring and continuing several (3 to 4) weeks, after which the adult beetle escapes.

Flat-headed apple tree borer Control. - Vigorous, healthy trees are not generally liable to attack, and cultural methods which will insure this condition are important. Trees headed low will shade their trunks and the sun-loving beetles will go to those exposed to sunlight. Shading trunks exposed to the sunlight, by boards cutting off this light, is a protection, as are also poles set in the orchard and covered with sticky material to catch and hold the beetles visiting them in search of places to lay their eggs.
Wrappings of burlap or paper extending from the ground to the limbs will prevent egg-laying but should be removed when this period is past. Birds and insect enemies aid in controlling this pest.

The Pacific flat-headed apple tree borer (Chrysobothris mali Horn) is found in the West. It is smaller than the last and rather dark coppery in color. The adults are found in spring and summer. The borers attack many kinds of trees and bushes and there is only one generation a year. Control measures are the same as for the last species.