THE FLORAL WORLD AND aARDEN GUIDE. 



225 



tend throughout tlie mass soou after the 

 tur.i of the year. Weii^h a few of the best 

 looking sets, and make those weighing two 

 ounces the standard for all. Those nearest 

 the size of two-ouuce tubers, sa^' from one 

 and a-half ounce to three ounces, will give 

 the best crops, and cost less than larger 

 tubers. The ground must not be trodden, 

 it must be in good heart, but without recent 

 manure. Wliere leaves are abundant, they 

 may be used to cover the sets, and seven 



incites of mould to be thrown over them. 

 As to injury from frost, there is no fear of 

 that, if they are covered sufRcieatly. The 

 after culture shoukl consist in frequent 

 flat-lioeing, but the plants should not be 

 eartlied up at all ; the practice delays 

 ripening, without increasing the bulk of 

 tlie crop. To be seven or eight inches 

 planted, is as much covering as the potato 

 can bear. g. H. 



THE PEAE ELY. 



(Communioatod to the Fruit Committee of the Koyal Horticultural Society.) 

 Dexia m<jt'ipes ? Walker; Diptera, pi. 12, 11. 



" I TRUST it will not be uninteresting to 

 the Fruit Committee if I call their attention 

 to the history of a little fly which, without 

 attracting the notice of the gardener, fre- 

 quently destroys his crops of pears, and 

 probably apples also ; and if to a know- 

 ledge of the economy of the insect I can 

 add a simple method by whicli its destruc- 

 tive effects raajr in future be prevented, or 

 at least reduced in extent, I shall not deem 

 the time mispent. 



"To Henry Webb, Esq., of Redstone 

 Manor, Reigate, a member of the late 

 Pomological Society, I am indebted for 

 sjveral specimens of Catlllac Pears, whicli 

 he sent me on the 25th of .June, 1860, in 

 which he had discovered several small 

 maggots, which caused the fruit to f:iU off 

 even at that early period. I at once placed 

 tiiem In a glass and covered them over, and 

 on opening it in February last I found 

 two flies had been produced, a male and 

 female, which I will endeavour briefly to 

 describe. 



"Tlie female is about tliree-cighths of 

 an inch long, appearing to tlie naked eye 

 of a pale gray colour, and in general for- 

 mation like a common house-lly ; but 

 under a lens its distinctive characters are 

 at once perceptible. Head semi-orbicular, 

 dingy white, with a black velvety mark 

 in front reaching down to the antennje, 

 and terminating at the back in form of a 

 crescent ; antcnnie dark, set with short 

 spines and slightly curved inwards ; eyes 

 rich brown, oval, widely separated ; thorax 

 ovate, angular at the base, with five re- 

 markable black spots, one on each shoulder 

 and three below, divided by a scarcely 

 perceptible suture ; several small black clots 

 between the larger spots, out of which stiff 

 sctte issue, the whole bearing a close re- 

 semblance to ermine ; scutellum semi-ovate, 



centre white, with an angular black spot 

 on each side, ending in a paint with a stifl 

 seta ; abdomen four-jointed, dingy white, 

 with three black spots on each joint, the 

 centre one angular ; wings dusky, long, 

 oval, with five principal nervures and 

 several transverse ; legs black. Under a 

 lens this is a very pretty fly, belonging to 

 the family muscidce, of which Mr. Curtis 

 enumerates forty-nine species in British 

 entomology ; but in the .absence of figui'es 

 and description I cannot identify it with 

 any of them. It appears, however, to cor- 

 respond with ' Dexia nigripes,' figured by 

 Walker, 'Diptern,' plate 12, fig. 11, al- 

 though he describes the thorax as quadri- 

 maculata, yet shows five sj)ots upon it 

 exactly according with ray specimen. The 

 male is smaller, of a more conunon dingy 

 colour and not handsomely spotted. The 

 maggots are very similar to those of the 

 blow-lly, but smaller. At what time the 

 eggs were deposited, or in what p.art, 

 cannot be precisely stated, but most likely 

 when the pear was in blossom, or very soon 

 afterwards, as I have frequently discovered 

 the larvce of Lepidoptera in the blossoms 

 of other trees, and bred them until they 

 arrived at the perfect state. I think it 

 would be almost impossible to destroy these 

 mischievous larvje or the flies at this time ; 

 but if every gardener who is made aware 

 of their destructive effects were carefully 

 to collect tlie fruits wliich they have caused 

 to fall abortive to the ground, and burn 

 them, the species above described might 

 ensily be kept under ; and by adopting tlie 

 same plan throughout the season, many 

 other equally injurious insects might be 

 almost extirpated, and thus tidiness and 

 usefulness would bo seen linked hand in 

 hand." " 



Cranjord, F. J. Graham. 



L 2 



