' A. E. Camkron 65 



As the puparium, which represents the shrunk larval integument, 

 retains the external characters of the larva in greater or less degree, 

 though not always so prominent, the same distinctions thus hold good 

 for the resting, as for the active, larval stage. 



The mouth apparatus is of the same general formation in all three 

 species, with the component sclerites practically similar in shape. 

 They only dilTer in quite small details almost negligible for purposes 

 of classification. A comparison of the cephalo-pharyngeal sclerites 

 of hyoscyami and bicolor shows that the upper subtended process of the 

 dorsal arm is relatively broader in the latter species (PI. I, figs. 15, 16 

 and 17, d.p.). In bicolor the angle formed by the hypostomal and inter- 

 stitial sclerites is more acute than is the case in hijoscyami, which is 45". 

 Further, the mandibular sclerites of bicolor bear dorso-posteriorly a 

 small, backward-curving denticular process (PI. I, fig. 17, d.f.), absent 

 in those of hyoscyami, which aids in forming a concavity for the arti- 

 culation of the distal extremities of the hypostomal sclerites. Again 

 the teeth or denticles borne by the mandibular sclerites of hyoscyami 

 arise more laterally than those of bicolor. The relation of parts is practi- 

 cally the same in bicolor and nigritarsis. 



These generalisations have been made on the evidence of numerous 

 specimens carefully examined, but I quite realise that the characters 

 may not be absolutely stable. In some cases as will be seen from the 

 foregoing remarks, the distinction of the species has a negative basis, 

 depending on the presence of some detail in one species which is absent 

 in another. This is often very useful for classificatory purposes, but 

 either the specimens must be examined fresh or precautions taken that 

 those examined have been well preserved. 



10. Remedies in England. 



Miss Ormerod collected much valuable information about the in- 

 festations of the mangold fly, which was incorporated in her reports 

 of the years 1880-95. Severe attacks were recorded periodically from 

 all parts of England, Ireland and Wales, from Cumberland and West- 

 morland in the north, where the species was first recognised about 

 1876 as a serious pest of mangolds in this country, to Devon and Cornwall 

 in the south-west. The years 1880 and 1891 were notable for the great 

 amount of damage done to this crop which was in many cases practi- 

 cally sacrificed to the ravages of the leaf-mining maggot. The same 

 author also noted that the incidence of the fly was generally associated 

 with the use of farmyard manure as a crop stimulant, especially when 

 Ann. Biol, i 5 



