416 INSECTS INJUROUS TO VEGETATION. 



fortnight afterwards. We have a kind of fly, corresponding 

 ahnost exactly with the description of the onion-fly. This 

 strengthens ray belief that our onions suffer from the depredations 

 of the maggots of this or of a similar insect. The fly to which 

 I allude is often found on windows in the spring. It is ash- 

 colored, with black hairs sparingly scattered on its body. It has 

 a rust-colored forked spot on the top of its head, and three rust-red 

 lines on the thorax ; and the wings are tinged with yellow near 

 the shoulders. It measures one fourth of an inch in length. It 

 is stated that there are two or three generations of the European 

 onion-flies_ during the summer, and that the late broods pass the 

 winter in the pupa state, and are ready to, burst forth at the first 

 warmth of the following spring. The only practicable plan for 

 destroying these insects that has been suggested, consists in pul- 

 ling up the onions as soon as they are found to turn yellow, and 

 putting them immediately into the fire. 



Some two-winged flies deposit their eggs in the stems, buds, 

 and leaves of plants, thereby producing large tumors or galls, 

 wherein their young reside. Others lay their eggs in fruits, on 

 the pulp of which their maggots live. These gall and fruit flies 

 belong to a family called Ortahdians (Ortalibid^J, from a word 

 signifying to flap or shake the wings ; for they keep their wings 

 in motion nearly all the time, jerking them up and down, and 

 twisting them round so that the thick outer edges often come to- 

 gether. Some of them are in the- habit of suddenly raising their 

 wings perpendicularly above their backs, and running along a kw 

 steps with them spread like the tail of a peacock. These insects, 

 together with several other groups of flies, differ from all the fore- 

 going in many respects, although they agree with them in their 

 transformations. The forehead is broad in both sexes; their 

 winglets are very small or entirely wanting ; their powers of flight 

 are feeble ; and they are rarely found sporting on flowers in the 

 sunshine, but seem generally to prefer shady and damp places. The 

 wings of the Ortalidians are often beautifully variegated, striped, or 

 spotted with shades of brown, or black. The hind-body in the 

 female generally ends with a pointed tube, wherewith the eggs are 

 deposited. The little white maggots often found in over ripe 

 whortleberries, raspberries, cherries, and other fruits, are the 



