361 



sap near the tube miglit set up an equally sudden increase of pressure 

 inside the egg, sufficient to induce hatching, is suggested as a possible 

 hypothesis, though more evidence on this point is necessary. 



Edwards (F. W.) & Williams (C. B.). Sciara tritici, Coq., a Fly 

 injurious to Seedlings. — Ann. App. Biol, London, ii, no. 4, April 

 1916, pp. 258-262. [Received 28th July 1917.] 

 Isolated cases of damage by the larvae of a species of Sciara were 

 reported from Surrey in 1911, the plants attacked being Primula seed- 

 lings, and from Yorkshire in 1915, in which case young orchids suffered. 

 The species concerned, which has not been previously recorded 

 in Great Britain or even in Europe, proves to be Sciara triiict, 

 known in N. America since 1895 as a severe pest of wheat and 

 orchard seedlings, of which it destroys the rootlets and young stems 

 just above and below the soil level. The adults on the wing can be 

 killed by regular nicotine fumigations, as they emerge at all hours 

 of the day, but the larvae and pupae seem to be immune to this treat- 

 ment. The original habitat of this fly is unknown, but its presence 

 in greenhouses is probably due to introduction in Osmunda fibre or 

 Sphagnum moss used in the cultivation of orchids. 



Rennie (J.). On the Biology and Economic Significance of Tipula 

 pahidosa. Part I. Mating and Oviposition. — Ann. App. Biol., 

 London, ii, no. 4, April 1916, pp. 235-210, 1 plate. [Received 

 28th July 1917.] 

 During the summer of 1913 and 1914, the mating and oviposition 

 of the crane-fly, Tipula paludosa, was studied both in the field and the 

 laboratory, where the larvae were kept in cages. The pupae were 

 transferred to small vessels of the size of flower-pots containing soi 

 and small pieces of turf, and covered with lamp-chimneys closed at 

 the top wdth pieces of cardboard. Hatching takes place at the end 

 of June or beginning of July, the earliest recorded date on which mating 

 M-as observed being 20th June. The results, which were always con- 

 sistent, showed that recently hatched insects pair most readily, and, 

 given the opportunity, do so a number of times. Oviposition takes 

 place soon after mating, though the presence of herbage as a stimulus 

 is necessary, no oviposition occurring on cottonwool, even if placed 

 above a layer of soil, nor on bare soil. Though these flies usually 

 oviposit among grasses, they may do so among standing corn. About 

 half a dozen eggs or less may be deposited at the same spot. The 

 eggs in a newly hatched female may be seen through the skin, but 

 these do not represent the whole number, there being a second batch 

 which matures later. The length of life of individual crane-flies has 

 not so far been determined. The flies kept in captivity were not 

 fed, but had access to growing grasses and to soil, both of which were 

 watered. 



Rennie (J.). On the Biology and Economic Significance of Tipula 

 paludosa. Part II. Hatching, Growth and Habits of the Larva. — 



Ann. App. Biol., London, iii, nos. 2 & 3, January 1917, pp. 116- 

 137, 3 plates. 

 Tipula paludosa is the commonest species of crane-fly occurring on 

 grasses and corn in the north-east of Scotland. Other species less 



