156 EXPERIMENT STATION RECORD. 



Practical microscopy. — An introduction to microscopical methods, F. S. 

 Scales (London, 1909, 2. ed., pp. XVI+33Ji; rev. in Nature [London], 82 {1909), 

 No. 2096, p. 245). — A second revised and enlarged edition. 



The southern plum aphis, C. E. Sanborn (Oklahoina Sia. Bui. 88, pp. 3-8, 

 figs. 5). — The southern plum aphis (Aphis setariw) appears annually on plum 

 trees in Oklahoma and unless controlled by natural means or by insecticides 

 practically destroys the plum crop. The new growth of the affected tree is dis- 

 torted, the leaves being more or less corrugated and crumpled together on the 

 lower surface. The terminal bud Ms stunted and its growth is sometimes 

 abruittly terminated. !Many of the blossoms are often killed, and in cases where 

 the infestation is severe early in the season, no fruit is set. 



Early in the spring the so-called stem mother hatches out from the egg, in 

 which stage it has passed the winter. Reproduction then takes place at a rate 

 of 2 to 5 young per day for a period of 3 or 4 weeks. These young attain their 

 growth in a week or 10 days and also reproduce raiiidly. Winged forms develop 

 which disperse and found new colonies. Early in the summer when the terminal 

 branches have nearly completed their season's growth and the leaves have be- 

 come toughened by age, dispersion becomes most pronounced. 



At this time the ai)hids commence to establish colonies on certain species of 

 grasses, namely, Canadian blue grass (Poa compressa) , crab grass (Panicum 

 sanguinalc), goose grass (EJusine indica), redtop (Tridens seslerioides) , yellovf 

 foxtail (CJicetochloa gl a uca), nimhle-wiU (Muhlenhergia schreberi) and P. poly- 

 anthes. When noticed upon grass they are often seen to be attended by ants, 

 such as Sdlenopsis dchilis. Miiioinorium ininutum, and S. geminata. 



The latter part of October the winged form, known as a migrant, arises from 

 the grass colonies and locates on the plum tree, there to found a new colony. 

 The descendants of these migrants differ greatly in function from their spring 

 find summer predecessors, from the fact that there are sexual forms, and the 

 females are oviparous instead of viviparous. When the oviposition is com- 

 pleted, which is usually by the middle of November, the aphids die. 



It is recommended that lime-sulphur wash be used at any time after the eggs 

 have been deposited in the fall and before the buds commence to swell in the 

 spring. Tobacco sprays are recommended for summer use. Lady beetles are 

 considered the most im])ortant of the natural enemies. 



The oyster-shell scale and the scurfy scale, A. I^. Quaintance and E. R. 

 Sasscer (U. 8. Dept. Agr., Bur. Ent. Circ. 121, pp. 15, figs. 2). — This circular 

 gives a summarized account of the life history and methods of control. 



The oyster-shell scale, a species of world-wide distribution, was introduced 

 into the New England colonies at an early date. In Canada and the Northern 

 States there is thought to be but one full brood annually, whereas in the 

 Middle and Southern States the species is double brooded. It has a wide range 

 of food plants, 109 being here listed, but is more commonly found on the 

 apple, maple, horse-chestnut, poplar, willow, and lilac. In some localities it 

 appears to be held in check by parasites, those more commonly found being 

 Aphelinus mytilaspidis, A. ahnormis, A. fuscipennis, A. diaspidis, Aspidiotiphagus 

 citriniis, Annphes gracilis, and ChcUoneurus diaspidinaruni. 



The scurfy scale, a nati\e of North America, occurs principally upon rosa- 

 ceous plants, such as the apple, peach, pear, plum, cherry, etc., and also on the 

 currant and gooseberry among cultivated plants. A list is given of 35 plants 

 upon which it has been found. It seldom becomes sufficiently abundant to 

 cause particular injury or to require specific treatment. " In the more north- 

 ern States there is but one brood each year, but in the South, as in Tennessee 

 and in (Georgia, there are evidently two full broods, and in the latter State there 

 is a strong probability of a third," Three predaceous species, Tyroghjphus 



