October 23, 1890] 



NATURE 



61 



flies, having first appeared in Great Britain in 1886, is 

 graphically described by Miss Ormerod, who has done 

 so much to familiarize agriculturists with the dreaded 

 scourge, and to make them acquainted with preventive 

 measures and remedies against it. This information, 

 published from time to time, is concisely summarized, so 

 that it may be said that, in the few pages devoted to this 

 insect, all that is known about it is plainly set forth. 



The least generally known facts connected with the 

 Hessian fly, and those of the most scientific interest, 

 relate to its parasites, which have been carefully studied 

 by the authoress, who had the advantage of long con- 

 sultations with Prof. Riley in 1887. 



The importance of the various parasites of the Hessian 

 fly in tending to keep it down in this country is great. 

 By some it is believed to be desirable to rear them 

 and take them to places that are badly infested, just 

 as, recently, parasites were imported from Australia to 

 destroy \)a.t. Icetya purchasi in the Californian orange 

 groves. It is certain that in this last summer the attack 

 of the Hessian fly was immensely modified by the para- 

 sites, which were present in unusual numbers. In several 

 instances where the pupae of the Hessian fly were trans- 

 ferred to live cages, at least 70 per cent proved to be 

 parasitized by at least three different kinds of flies. Miss 

 Ormerod and Prof. Riley agree that the parasites of the 

 Hessian fly in Great Britain are of the same species as 

 those found in Russia, and differ from those which infest 

 the Hessian fly in America. Comparative lists of the 

 American and Russian Pteromali are submitted, from 

 which it is seen that they are of the same genus, but not 

 ■of identical species. " The examination of our parasites," 

 Miss Ormerod concludes, "pointed, therefore, very strongly 

 to the probability of our Hessian fly attack having been 

 imported to us from the east of Europe." And, further, 

 it is suggested that it originated, not in straw imports, as 

 it was first imagined, but in the pupa, or "flax-seed," 

 condition in foul grain imports. 



In Part II., devoted to the insects that injure forest- 

 trees, among the principal offenders is shown to be 

 the elm-bark beetle, Scolytus destructor, which makes 

 the well known galleries between the bark and the wood, 

 " mainly in the soft inner bark, but so as to leave a slight 

 trace of the working on the surface of the tree." This 

 beetle often causes serious injury to elms both in this 

 country and on the Continent. It generally attacks trees, 

 or the parts of trees that are inclined to disorder, or 

 decay, or that have been previously attacked by beetles. 

 To circumvent the operations of this insect, Miss Ormerod 

 recommends that the rough bark should be scraped off", 

 so that the larvae are exposed to air, or driven out by the 

 flow of sap from the inner lining of the bark. This was 

 found to answer in France, where upwards of 2,000 trees 

 were thus treated. 



The ash-bark beetle, Hylesinus fraxini, injures ash 

 trees in the same manner by making galleries beneath 

 the bark, particularly in young trees. It is advised that 

 the bark should be treated with a good coat of soft soap 

 well rubbed into the affected parts of the trees. 



Yet another boring beetle is given, known as Hylurgus 



piniperda, or pine beetle, injurious more on account of 



the harm the beetles cause by boring through the side 



of the tender shoots of young pine trees and eating their 



NO. I095; VOL. 42J 



way for an inch or more along the pith, than from the 

 galleries made by the larvae in pine timber. As they 

 often select dead or diseased trees for boring into for 

 breeding purposes, felled trees should be at once removed 

 and diseased branches or limbs of trees in infected woods 

 should be cut off" and carried away. Or traps may be set 

 for the beetle by placing "young Scots pine tops, thinning 

 off" all the branches (which makes them convenient to 

 handle) in the plantations or against the lower part 

 of the standing trees." The beetles select these for 

 laying their eggs upon, and they should be taken away 

 and burned in June. 



Another pine beetle, Hylobius abtetis, is even more 

 injurious to many of the coniferae than the Hylurgus. It 

 may be entrapped in the same manner, as it frequents 

 forest clearings, that is, where fir trees, few or many, have 

 recently been felled, and lays its eggs also on logs and 

 stumps. 



Against the attacks of many other insects troublesome 

 to trees, such as the pine-bud moth, the pine-shoot moth, 

 the pine saw fly, the spruce gall aphis, the larch aphis, 

 the willow beetle, and the oak-tree roller moth, methods 

 of prevention and remedies are prescribed. This part of 

 the " Manual " cannot fail to be most instructive and useful 

 to those in charge of woods and forests. 



In Part III., treating of fruit-crops and insects that 

 injure them, twenty-three diff"erent insects are fully de- 

 scribed, and in all cases practical suggestions are made 

 for preventing their onslaughts upon the fruit crops, and 

 for diminishing the virulence of their attacks. These 

 suggestions are most timely, as during the last few years 

 the fruit crops of almost all descriptions have suff"ered 

 much from insects. Not only have new kinds of insects 

 arisen, but long-known foes have increased and multiplied 

 to a terribly dangerous extent, so that whole districts 

 have been cleared of fruit. For example, in the spring 

 of each of the last three years hosts of caterpillars of 

 several species have ruined the apple, plum, and damson 

 crops in many parts of Kent, and in other fruit-producing 

 counties. 



Among the fruit pests that have recently sprung up 

 are the white woolly scale, Pulvinaria ribesit, found 

 last year upon currant bushes to a considerable extent. 

 A figure of a currant twig covered with white cottony, or 

 woolly matter, forming a covering for the eggs and young 

 scales is appended, which conveys a good idea of the 

 " almost overwhelming nature of the infestation and the 

 serious amount of injury caused by it." This attack has 

 been known in France for some time, and is mentioned 

 by Signoret in his " Essai sur les Cochenilles." Miss 

 Ormerod recommends applying limewash to the infested 

 bushes with a brush, " the same process as whitewashing." 

 Where remedies cannot be brought to bear, or fail, "it 

 would be best to cut off" and burn the infested branches, 

 or to destroy and burn the infested bushes if it could be 

 done without serious loss, and thus stamp out this newly- 

 observed pest in time." 



A fruit-tree boring beetle new in this country, but well 

 known in Germany and America, from whence it was 

 probably imported, was identified by Miss Ormerod in 

 1 889 as the " Shot-borer," Xyleborus dispar. This was 

 found in Lord Sudeley's fruit plantations in Gloucester- 

 shire, in the stem of a young plum tree into which it had 



