711 



Avhich had been blown from 220 yards to 13| miles or more, as verified 

 by the wind records taken at or near those points. Three larvae were 

 also taken from two large screens on the hills of Xew Hampshire during 

 1911. The screens used on the coast were of | inch mesh poultry- 

 wire fastened to posts 12 feet high. Considering the great numbers 

 of larvae taken in the above experiments, there can be no doubt that 

 the wind is almost wholly responsible for the general spread of L. dispar 

 in Xew England. To prevent continual spread by the wind into new 

 territory the badly infested areas near the border must be brought 

 under control either by natural enemies, or hand methods, or both. 

 The former are now playing an important role in the control of this 

 insect in the greater part of the infested territory. The larvae are 

 sufficiently active and allow themselves to be transported by the wind 

 at temperatures of 55° F. and above, and have been caught at wind 

 velocities varying from 2 to 23 miles an hour, although more active 

 spread takes place when the temperature ranges from 65° to 85° F. 

 and when the velocity reaches 8 miles or more an hour. Larvae are 

 involuntarily carried by sudden gusts of wind when the temperature 

 reaches 50° to 55° F., at which temperatures they often start crawling. 

 By far the larger number of larvae were borne by combinations of 

 west winds. The general progress of the species since its establishment 

 at Medford, Mass, , at the rate of 5 miles per annum to the north-east and 

 at the rate of 3 miles per annum westwards from Providence, R.L, since 

 its first appearance there in 1901, tends to verify the data collected 

 in connection with the screen experiments. A bibliography of eight 

 works is appended to this paper. 



Sevkrin (H. H. p.), Severin (II. C.) & Hartung (W.). The Stimuli 

 which cause the Eggs of the Leaf-ovipositing Tachinidae to hatch. — 



Psyche, Boston, 2Iass., xxii, no. i, August 1915, pp. 132-137. 



Eggs of Chaetogaedia moYdicola, Bigot, were obtained from adults 

 kept under slightly moist conditions and supplied with food consisting 

 of banana pulp and sugar. Experiments were performed to determine 

 whether the eggs would hatch in the juices emitted from the mouths 

 of a number of the normal hosts. Hatching took place readily in the 

 green alkaline liquid ejected by larvae of Cirphis {Heliophila) unipuncta, 

 Haw., Vanessa cardui, L., and Phytometra {Plnsia) chalcites, Esp. 

 A similar experiment was performed with Anosia plexippus, L. 

 (milkweed caterpillar), from which this parasitic fly has not been 

 bred, but the eggs nevertheless hatched. Many eggs failed to hatch 

 in acid media, obtained from the body fluid of C*. unipuncta and 

 A. plexippus and from blades of grass on which the eggs had been 

 deposited. Immersion in sodium hydroxide solution (Ol and 0"05 

 per cent.) and in distilled w^ater caused emergence of the larva in from 

 36 to 60 hours. Since many eggs of C. monticola hatched in one minute 

 in the juices ejected from the host, Townsend's view that the juices 

 act on the chitin and cause the shell to w^eaken is probably incorrect. 

 In all probabiUty the digestive juice of the host is perceptible to the 

 larva through the micropyle of the egg and it immediately endeavours 

 to free itself. 



