August 2 2, 1889] 



NATURE 



387 



extracts will be received with much interest by all 

 economic entomologists. 



"The perfect insect is one of the most beautiful of 

 the order to which it belongs ; the male is singularly 

 -distinguished by having two slender filaments arising 

 between the eyes, knobbed at the tips, a peculiarity 

 which we believe is possessed by no other dipterous 

 insect, and which is wanting in the female. The larva 

 is a white, fleshy grub destitute of legs, very similar to 

 the celery fly, and like it possesses two small black 

 hooks at the front of its body, which it alternately pro- 

 trudes and retracts, thereby tearing the delicate membrane 

 in which the drops of juice are contained. There are 

 _generally several of these larvae in each orange, and when 

 removed and placed upon a flat surface, they have the 

 power of springing to a considerable distance, in the same 

 manner as the well-known cheese-mite. When full-grown 

 they eat their way out of the orange, and undergo the 

 change to the pupa state on the outside." 



Prof Westwood adds that the presence of infestation 

 might be inferred sometimes by a puncture not larger 

 than that made by a pin, but generally surrounded with a 

 withered and discoloured spot varying in size from six- 

 pence to half-a-crown. 



Miss Ormerod characteristically observes : — 



" One main point of information wanted to check attack 

 is, Where does the maggot in natural circumstances under- 

 go its changes to the chrysalis state ? It might be found out 

 very easily whether the maggots drop to the ground, by 

 laying cloths smeared with any sticky material, which would 

 prevent their straying away, beneath a few of the infested 

 trees. Any fruit that is infested should not be allowed to 

 remain on the ground to continue the attack, and if on 

 investigation it should prove that the later maggots go 

 into the chrysalis state in the ground, or even that a large 

 proportion of them do so — or if it could be found where the 

 flies generally hibernate —these points would help greatly 

 in lessening attack." 



Ostrich-farming, extensively adopted in South Africa, is 

 much hindered by " a terrible pest," in the shape of the 

 ostrich flies, of which sometimes there are " thousands on 

 the ostriches, and that they irritated the birds so that half 

 of their time was taken up in pecking at the flies, and 

 that, judging from the increase in the last two years, if 

 something was not done to destroy them, the feathers 

 would not be worth sending to market, and the writer 

 believed that in time they would destroy the birds." 



The fly in question is akin to the "forest fly" {Hippo- 

 bosca equince), which is -found upon horses and ponies 

 in the New Forest, in Hants. These get accustomed to 

 the flies, and make no special demonstrations concerning 

 them ; but a horse which is strange to their attacks goes 

 half mad when one of these insects gets upon it. 



In the case of ostriches, Miss Ormerod considers 

 tobacco decoctions, soapsuds, and other washes applied 

 to the birds would be found to succeed. McDougall's 

 dip has been used, and Miss Crmerod thinks that sulphur 

 would be useful. 



Cattle ticks {Amblyomma hebrceufn), of the family 

 Jxodidcs, some of them three-quarters of an inch long 

 by three-eighths wide, described as the " disastrous hide 

 perforators of these regions," sadly vex the South African 

 cattle, so that it would indeed be a boon to the country 

 if any means could be discovered to destroy, or, what 

 would be better, " prevent the presence of a little 



creature which moves a market downwards at a high 

 percentage." 



The most interesting part, perhaps, of this work is that 

 which deals with some of the Coccida. P'irst among 

 these is the " Australian bug'' {Icerya purchasi), which was 

 noticed in the Botanic Garden at Cape Town in the latter 

 half of 1873, and has now spread over 680 miles in the 

 eastern provinces of Cape Colony. Where it came from, 

 Miss Ormerod says, it does not appear, " but there is not 

 room for doubt that the attack was set on foot by imported 

 specimens, and that it rapidly became naturalized. It 

 attacks" orange trees, vines, fig trees, deciduous fruit- 

 trees, ornamental shrubs, and garden plants, even straw- 

 berry plants. 



The life-history of this insect is remarkable. When 

 the female, a salmon-coloured, tortoise shaped insect, 

 with six legs and long antennae, is one-sixth of an inch 

 long, it secretes snow-white cotton-like matter, which is 

 formed under the mother for the covering and protection 

 of its eggs. For some time the female moves about, but 

 after a while all movement is arrested, and the insect 

 seems glued to one spot. In time the eggs are hatched, 

 and larvas, as many as 200 often from one female, go forth 

 to find congenial food upon the plant, and in turn lay eggs 

 in the same manner. The eggs are not hatched at once, 

 but the process continues for several weeks. In the 

 meantime the mother shrivels up, and becomes a mere 

 dead husk, covering the eggs and hatching young. The 

 whole process extends over many weeks, and gives ample 

 opportunity for immense damage to be caused. 



The male is rarely seen. It has wings more than a 

 fourth of an inch in expanse ; its body is about the eighth 

 of an inch long, orange-red in colour, with long ten-jointed 

 antennas. Prof. Riley gives the best account of the male 

 insect, stating that it is " fond of shelter, and will get under 

 any projecting piece of bark or under bandage placed 

 round the tree, often creeping under clods of earth. It is 

 rather sluggish during the day, remaining motionless in 

 crevices of the bark or wedged in between females on the 

 tree. There seems, in fact, a well-marked attempt at 

 concealment. At the approach of night they dart rapidly 

 about on the wing, swarming round infected trees." 



Miss Ormerod prescribes various washes as remedies 

 against this and other coccids, and gives a list of insect 

 enemies, which are happily numerous and formidable. 

 The larva of the " golden eye " {Chrysopa perla) is most 

 useful, destroying the young "Australian bug" just at 

 hatching-time within the sac of the female. The Chrysopa 

 also devours quantities of Aphides which infest hop plants 

 in England. Species of ladybirds {Coccinellce) are by far 

 the best friends to African cultivators. They are invalu- 

 able in destroying the perfected young in the nidus of 

 the female " bug," just as they, both as larvae (niggers) 

 and perfect insects, eat myriads of hop Aphides in the 

 English plantations. 



There are other insects which do good service in keep- 

 ing down this Icerya, described by Miss Ormerod, of 

 which, however, there is not space to give any account. 

 Other destructive and useful insects have not been alluded 

 to for the same reason, but those who take an interest in 

 economic entomology will do well to peruse this in- 

 structive little book, and extract for themselves its 

 valuable contents. 



