1919] ECONOMIC ZOOLOGY ENTOMOLOGY. 163 



make 50 gal., is effective in combating tlie potato plant louse, all the aphids hit 

 by tlie spray being killed. The materials used for the emulsion cost about half 

 as much as for nicotin solution, and possessed the additional advantage of 

 being obtainable at any grocery store. 



Life history and habits of the mealy plum, aphis, W. M. Davidson (U. S. 

 Dept. Agr. Bui. 774 (1919), pp. 16, pis. 2). — For many years the mealy plum 

 aphis (Hi/alopterus arundinis) has been a source of injury in California to 

 plums and prunes, and to a lesser extent to apricots, having been specially 

 severe in some regions since 1913, particularly where artificial control of the 

 pear thrips was not practiced. 



Though of European origin, the species is widely distributed in North 

 America and is known to occur in Australia, New Zealand, Java, and Japan. 

 In California plums and prunes of the P. domestica type are the favorite hosts, 

 but apricots and Asiatic types of plums and rarely almonds are also attacked, 

 while in Europe grape, peach, and nectarines are attacked. Its injury is caused 

 in the early summer months on the lower surface of the leaves and the petioles 

 and upper surface are frequently infested. The young fruit is less commonly 

 attacked. Tlie leaves become curled and discolored and the tree produces fruit 

 of small size and an early drop. In the years 1915 and 1916 an unusual mid- 

 summer apical cracking of green prunes developed in California. 



The eggs, which are almost invariably laid in the axils of lateral buds of 

 year-old or 2-year-old wood, commenced in 1916 to hatch about March 4 and 

 continued for about Z weeks. The early stem mothers began reproduction about 

 March 20. Observations made at Walnut Creek between August, 1915, and 

 December, 1916, are summarized as follows : " It appeared that normally from 

 3 to 5 generations were raised on the winter hosts, but rarely series of wingless 

 generations persisted until the fall. The aphids of the earlier generations 

 were mostly wingless like the stem mothers, and the individuals of the later 

 generations mostly winged, and after the middle of June virtually all the insects 

 produced developed wings. 



" Migration to the summer hosts, Phragmites and Typha, began the last week 

 in April and continued until August, the great body traveling in early June. On 

 these hosts about ten generations took place, continuing up to November. The 

 vast majority of aphids to be found during the summer were wingless, but 

 winged parthenoparous individuals were also produced on the summer host 

 plants, and these served to distribute the species among these plants. About 

 the middle of October and for six weeks succeeding, winged sexuparous 

 migrants and winged males were produced, and these flew to the fruit trees, 

 whereupon the sexuparse proceeded to deposit sexual females. The sexes were 

 most abundant during the forepart of November and were to be found as late 

 as the middle of December. Oviposition took place throughout November and 

 December, the majority of ova having been placed before December 10." 



Mention is made of a number of predatory enemies, of which it has many, but 

 internal parasitism is said to occur rarely. 



" There are two specially vulnerable periods in the annual life cycle of the 

 mealy plum aphis — one in early spring when the stem mothers are growing and 

 the other in late fall when the sexual females are developing on the winter 

 hosts. . . . Contact insecticides, which have little effect on aphids of the inter- 

 mediate generations, easily destroy the stem mothers and the egg-laying 

 females." 



Seventeen-year locusts due in western Ohio, H. A. Gossard (Mo. Bui. Ohio 

 Sta., Jf (1919), No. 4, pp. 124-128, fig. i).— This article calls attention to the ex- 

 pected appearance of the periodical cicada over the western half of Ohio 



