Page 4 



BETTER FRUIT 



June, ip30 



Apple tree first year afler transplanting, girdled and 

 killed by flat-headed apple tree borers. 



like ovipositor into the opening and 

 then remains quiet for a few seconds 

 while the egg is being placed. After 

 the egg is disposed of she moves on in 

 search of other places for ovipositing. 

 It very frequently occurs that one or 

 more females, while engaged in egg 

 laying, will visit a single opening in 

 the bark several times, resulting in a 

 small group of eggs being placed near 

 together. The borers hatching from 

 such groups of eggs feed away from the 

 center in opposite directions, and often 

 eat out a large connected series of bur- 

 rows. 



The Egg 

 The egg, which is pale yellow in 

 color, is flattened, disk-like, and 

 wrinkled, and is about one-twentieth 

 of an inch in diameter. It is attached 

 firmly to the bark by its flat surface 

 and hatches in from 15 to 20 days. The 

 eggs are usually concealed beneath a 

 scale of bark or within a crack or 

 wound in the bark. A single female 

 probably produces on an average not 

 far from 100 eggs. 



The Larva 



The larva is a yellowish-white, 

 footless grub, which attains a length of 

 about one inch. The three segments of 



the body next to the head are 

 swollen and flattened, which 

 accounts for the names "flat- 

 head" and "hammer-head," by 

 which the species is commonly 

 known. The larva is usually 

 found curved like a horseshoe, 

 and is sluggish and inactive ex- 

 cept in very warm weather. 



On hatching, the larvae usually 

 enter the bark from directly 

 l)cnealh the egg, and, if the 

 wood is in favorable condition, 

 burrow at once into the inner 

 bark, where they feed on the 

 bark and sapwood and develop 

 rapidly. If, on the other hand, 

 the tree is vigorous and full of 

 sap, the borer is unable to 

 thrive within the growing tis- 

 sue and may soon die or may 

 live for months just beneath 

 the hard outer layer of bark, 

 where it obtains barely suffi- 

 cient food to maintain life. Un- 

 der such conditions the borer 

 sometimes lives for a year or 

 longer, surviving the cold of 

 winter but making scarcely any 

 growth. In time it dies a slow 

 death by starvation, unless that 

 part of the tree where it is 

 located should become sufTi- 

 cienlly enfeebled for the borer 

 to penetrate to the inner bark 

 undisturbed by the flow of sap. 

 Where such a condition arises 

 the previously starved borer 

 begins at once to grow and de- 

 velop, but its period of exist- 

 ence in the tree may be length- 

 ened by a year as a result of 

 unfavorable conditions in its 

 early life. 



Under favorable conditions 

 the transformation from egg to 

 adult covers a period of one 

 year, but where the develop- 

 ment of the larva is retarded by insuf- 

 ficient food, as described above, the 

 period may be lengthened to two years 

 and possibly longer. 



It not infrequently occurs that the 

 bark of trees that are but slightly on 

 the decline, or, especially, those that 

 have assumed a leaning position so that 

 the sun's rays fall directly upon the 

 trunk, will contain constantly for years 

 these little, starved flat-headed borers 

 that are unable to come to maturity. If 

 such trees continue to decline, the time 

 is sure to come when the borers can 

 penetrate to their favorite feeding place 

 and complete their transformation. 

 After this the injury to the tree is likely 

 to increase rapidly. 



Late in the summer the borers that 

 are approaching maturity burrow ab- 

 ruptly into the wood to a depth of from 

 less than an inch to several inches, and 

 at the end of their slender gallery in 

 the wood construct a flattened pupal 

 chamber in which they pass the winter. 

 After the borer settles in the pupal 

 chamber its color changes to a deeper 

 shade of yellow. In the southern part 

 of its range pupation often takes place 

 within a cell constructed between the 

 bark and wood, adjacent to the feeding 

 galleries. 



The Pupa 



The pupa averages one-half inch in 

 length and one-fourth inch in width, 

 and resembles in shape and dimensions 

 a small pumpkin seed. When first 

 formed it is yellowish-white, but later 

 its rudimentary eyes, legs, thorax and 

 other parts of the body take on a me- 

 tallic brown color. In from three to 

 five weeks it transforms to the adult 

 stage and the beetles escape from the 

 wood by means of the entrance gal- 

 leries of the larva;. 



Natural Enemies 

 The flat-headed apple-tree borer falls 

 a prey to a number of natural enemies 

 which destroy it during its larval, pu- 

 pal, and adult stages. Woodpeckers de- 

 vour many of the insects by penetrat- 

 ing to their feeding places in the wood, 

 and the United States Biological Survey 

 has found the beetles in the stomachs 

 of the common crow, kingbird, and red- 

 eyed vireo. Among insects, ants seek 

 out and devour both larvae and pupae 

 while they are in the wood, and six 

 hymenouterous parasites are known to 

 attack the species. 



Methods of Control 



In the control of the flat-headed 

 borer nothing is more important than 

 such cultural methods as will keep the 

 trees in a normally vigorous and grow- 

 ing condition. Such trees are rarely, 

 if ever, injured. All the well-known 

 orchard practices, such as cultivation, 

 fertilization, spraying, and pruning, 

 have an important effect in lessening 

 the possibilities of injury from flat- 

 headed borers. Such practices tend to 

 keep the trees thrifty and resistant to 

 borer attack. 



Trees should be maintained in an up- 

 right position, and, where practicable, 

 should be headed low in order to re- 

 duce the chances of sun-scald and win- 

 ter crackling and killing of the bark, 

 both of which invite borer attack. Low- 



Leaning apple tree with trunk exposed to 



direct rays of the sun. P'lal-headed borers 



may always be looked for in such trees. 



