6io 



NATURE 



[October 23, 1890 



case is that carrot-growers should thin carrot plants early, 

 and draw the soil as close as possible, and make the 

 soil very firm around them immediately after thinning 

 has taken place. 



Again, " although the summer broods hatch in three or 

 four weeks the maggots may be found in the roots during 

 the winter, and they change to pupae in the earth adjacent. 

 It is therefore very desirable that all infested carrot-beds 

 should be thoroughly cleared of roots in the autumn, and 

 the ground well dug, or trenched, so that such maggots or 

 pupae as remain in the bed may be destroyed ; some may 

 escape, but the larger number will thus be buried too 

 deeply to come up again or be thrown on the surface to 

 the birds ; and a dressing of gas-lime will be serviceable 

 in destroying such of the maggots as are lying near the 

 surface." 



Remedies are prescribed for this attack in the shape of 

 dressings with spirits of tar mixed with sand, and of 

 paraffin oil and sand ; also waterings with dilute soluble 

 phenyl and paraffin oil, in the proportion of a pint of 

 paraffin to two gallons of water. 



Among the many insects that injure corn crops whose 

 histories appear in this " Manual," is a group of flies, 

 among which are the frit fly iOscinis frit) — a minute fly, 

 not the eighth of an inch long, whose attention seems to 

 be confined to oats. The maggot coming from the tgg 

 laid by this " fly feeds in the heart of the young oat-plant 

 a little above the ground-level and eats away the centre, 

 60 that the shoot above the eaten part is destroyed, and 

 the damage that is going forward then becomes noticeable 

 from the injured shoots turning brown and withering 

 instead of continuing their growth." 



The frit fly has been well known in France, Germany, 

 and particularly in Sweden, where it attacks barley, but 

 until 1888, when the attacks of the frit fly were very 

 prevalent in Devon and Cornwall, not much was known 

 of it in this country, although, as Miss Ormerod points 

 out, " the presence of the Oscinis vastator, Curtis, which 

 appears to be the same as Oscinis frit, was watched and 

 recorded in 1844 by John Curtis in his 'Farm Insects.' 

 In 1 88 1 I was favoured by Mr. R. H. Meade, of Bradford, 

 with the information that the Oscinis frit had been ob- 

 served in the autumn of that year in swarms in an out- 

 building, in the lofts of which a lot of newly-threshed 

 barley had been stored, which points to the Swedish form 

 being then present ; but it was not until 1887 that I was 

 able to watch this attack throughout its course, up to the 

 development of this fly as a regular field attack." 



Farmers now find another fly, the " gout " fly, or ribbon- 

 footed fly, Chlorops tcsniopus, to be a frequent enemy to 

 wheat, rye, and barley plants. This, as shown in the 

 " Manual," is most prevalent on barley, and is mentioned 

 by Curtis as having done much harm, in 1841, in Surrey 

 and Lancashire. Now it is found in most parts of the 

 country, and is a striking instance of the general spread 

 of insect pests within the last few years among cultivated 

 crops of all kinds. 



The action of this insect is thus described by Miss 

 Ormerod :— " Whilst the plant is still young and the form- 

 ing ear is wrapped in the sheathing leaves, the fly places 

 her eggs either within these leaves or so that the maggot 

 can make its way through them to the ear ; there it 

 usually eats away some parts of the lower portions of the 

 NO. 1095, VOL. 42] 



ear, and then gnaws or, rather, tears a channel down one 

 side of the stem to the uppermost knot, and beneath the 

 leaves the maggot changes to a reddish chrysalis, from 

 which the gout fly appears about harvest time." 



It has been a moot point where this insect passed the 

 winter in this country. In Germany, as Taschenberg 

 states in his Praktische Insekten Kunde, the flies place 

 their eggs on grasses and autumn sown corn, upon which 

 hibernation takes place either in larval or pupal form. 

 As reported by the Consulting Entomologist of the Royal 

 Agricultural Society of England, pupae of the chlorops 

 were discovered in the main stems of wheat plants just 

 above the ground, in England, in the early part of the 

 spring of 1890 by Mr. Whitehead. The time when these 

 were found and the evident injury caused to the plants 

 proved that the insect had hibernated within their stems. 



Another insect belonging to the group of corn flies is 

 the corn saw fly, Cephus Pygmaus, a very small insect 

 which pierces the stem of wheat and barley plants "just 

 below, or at one of the knots, and inserts there an Qgg, 

 continuing this process successively to other stems until 

 her egg supply is exhausted. The maggot, which hatches 

 in about ten days, is about half an inch long, yellowish 

 white, fleshy, with a horny, rusty-coloured head, and is 

 peculiar in being footless, although the larva of a saw fly. 

 It feeds on the inner substances, clearing its way some- 

 times through the knots, even through the topmost, and 

 when nearly full-grown comes down inside the stalk on 

 which it has fed ; and about harvest time, or a little 

 before, it comes down to the ground level, where it gnaws 

 a ring so neatly and cleanly round inside the stem that 

 the straw readily falls with its own weight, or from a slight 

 pressure of the wind, the severed stalk showing almost as 

 smooth a fracture as if it had been separated by a knife. 

 When the maggot has thus travelled down the stalk and 

 nearly cut it through (so that nothing may prevent its 

 escape presently as a fly) it goes down into the lowest 

 part and spins itself a silken case in which it passes the 

 winter." 



The wheat-bulb fly {Hylemia coarctatd), though only 

 identified in 1882, has now become one of the pests to be 

 dreaded by wheat growers. Curtis does not speak of it, | 

 and it was first distinguished in this country by Miss I 

 Ormerod. Taschenberg speaks of this fly as destructive 

 in parts of Germany, and says there are two broods there. 

 As this seems to be a new destroyer here, it is possible 

 that it was brought from Germany with imported straw 

 or produce of some kind. 



In the " Manual " it is observed that the attacks of the 

 maggots of the wheat-bulb fly and those of the frit fly are 

 much alike, so far as the method of injury is concerned. 

 But here Miss Ormerod's entomological knowledge and 

 acute perception of the smallest distinctions serve to 

 show how the different flies may be recognized. In the 

 maggot or larva of the wheat-bulb fly " the tail segment 

 projects, and ends in two squarish-ended teeth with 

 flattened edges placed centrally, with one pointed tooth, 

 and sometimes more, on the central square part. . . . 

 The presence of these teeth and the absence of a little 

 bunch of stalked spiracles near the head appear to me to 

 be the simplest way of knowing the wheat-bulb from the 

 frit maggots." 



The Hessian fly, another member of the group of stem 



