Insects in Orchid Houses. 109 



bour's carrot-bed ; every carrot has been ruined ; his bed is utterly 

 ruined." Together with the work of the Carrot Fly in this neigh- 

 bourhood was a bad attack of Aphis. " People about here," writes 

 Mr. Hammond, " are complaining that their carrots are very much 

 infested with Aphides at the roots." This was early in October. 

 By the 20th Mr. Hammond found that they had nearly all dis- 

 appeared. They are to be found generally on the crown of the 

 carrot ; they do not cause the cracks, but shelter in them. These 

 Aphides were too shrivelled to identify when they arrived ; they 

 were probably Schizoneura fodiens. 



Correspondence and Report on Insects in Orchid 



Houses. 



Gatton Pabk, Surbey, 



Btn July, 1902, 



To Pkofessor E, Ray Lankester, M.A., etc., 



Natural History Museum, South Kensington, S.W. 



My Dear Sir, — I am a collector of orchids and somewhat largely 

 interested in their hybridization, but our efforts are materially interfered 

 with by a little fly or its grub (specimens of which I enclose), and whose 

 ravages we have found no means of preventing. It is no uncommon 

 thing for them to clear off the whole of the contents of a pot of seed as 

 soon as it is sown and germinates. We have made the following observa- 

 tions in regard to it : — 



They seem to frequent and thrive most where they have damp moss to 

 dwell in, which unfortunately is an essential feature of successful orchid 

 growing. 



Being often found on plants that have no seed on them, they of course 

 have other food, but apparently they have largely increased in my houses, 

 which, however, may be due rather to the amount of moist moss about than 

 to the amount of orchid seed which they have to feed on. They are 

 equally troublesome in what we know as the " Cool House " (50° to 00° F.) 

 as in the hot ones (65° to 85° F,). They devour the seed immediately it 

 commences to germinate, and if not devoured in this stage they attack 

 the small bulblet as soon as it is formed, eating it from the base and 

 leaving the shell only. They are harmless to plants after the early stages 

 and so are not troublesome to orchid growers generally. 



Careful search has failed to discover a grub. Hence it is assumed 

 (possibly erroneously) that it is the fly which does the mischief. Further, 

 the winged one (? male) is rarely found on the pots, which leads to the 

 assumption that it is the wingless one which does the mischief. If we are 

 wi'ong in the assumption that the male only has wings our observation 

 would lead to the suggestion that the fly is harmful only before it develops 

 its wings. The body of the wingless one on the pots is much larger than 

 the one found with wings. When the seed is sown on a flat surface 

 without harbour we are not troubled ; but directly the seed is removed, 

 which it has to be soon after germination, it becomes liable to attack. 



