ECONOMIC ZOOLOGY ENTOMOLOGY. 755 



Rcnuciff. Agr. [Paris], 8 (1909), 'So. 1, pp. //^-5/). — This is a ivport of experi- 

 uients t'oiuliK'ted in Uruguay with contact and stomach iK)isons. 



While as high as 82 per cent were Icilled by contact sprays this method is 

 only api)llcable to gardens, small fields, and orchards. For more extensive op- 

 erations sweetened arseuicals must be used. In order to obtain the best results 

 the author considers it necessary to establish a well-organized force in the 

 localities where the locusts are known to breed. It is also deemed desirable that 

 the governments of Uruguay, Paraguay, Argentina, and Brazil cooperate in 

 dealing with the pest. 



Contribution to the knowledge of the chemical composition of migratory 

 locusts, their eggs, and young, J. Schrokdkb (ZtscJir. I'flaiizcnkrank., 19 

 (1909), \o. 1, pp. 13-18). — The results of analyses here reported show that the 

 migratory locust is much richer in nitrogen and phosphoric acid but poorer in 

 potash than is liarnyard manure. 



Papers on deciduous fruit insects and insecticides. The pear thrips and 

 Its control, D. Moulton (U. S. Dcpt. Agr., Bur. Ent. Bui. SO, pt. .'/, pp. 51-66, 

 pis. 3. fiffs. 5). — In continuation of investigations previously noted (E. S. 11., 19, 

 p. 453), it is announced that the adult thrips cause scab on pears, while the 

 larvjie produce scab on prunes. The adults accomplish their feeding by rasping 

 the tissues and sucking out the plant juices in the early buds and blossoms. 



Studies of the seasonal history and habits of the pest are reported. Eecords 

 kept of the emergence from the soil of adults from 4 orchards in the Santa 

 Clara Valley in 1909 show the first to have been collected on February 15, while 

 by February 25, they wei'e common in all orchards. The maximum emergence 

 begins about February 19 and continues until about March IG. Practically all 

 the thrips were out of the ground by March 20. A lack of food supply causes 

 the adults to migrate, and the fact that migration often takes place before the 

 period of oviposition begins explains why the thrips may injure an orchard 

 during one season and seem to have almost entirely disappeared from it the 

 next. In 1909, oviposition was first observed on 31arch 10. Larvie hatch out 

 in about 4 days and seek sheltered places between rolled or folded leaves or 

 in blossoms or lie close along the veins on some of the larger leaves. They 

 reach full growth after 2 or 3 weeks, drop to the ground and penetrate into it 

 for several inches where they enclose themselves in a tiny cell and remain 

 during all the rest of- the year. While they usually remain in the 3 or 4 in. of 

 harder ground immediately below the surface, where the soil is loose owing to 

 a shallow spring cultivation, they penetrate to a much greater depth and have 

 been found at a depth of from 15 to 16 in. The period of pupation begins in 

 September and reaches its maximum during October, November, and December. 



Practical and efficient measures have been perfected for the control of this 

 pest. 



"To gain complete control of the pear thrips, both plowing and spraying 

 should be adopted as remedial. Land should be plowed as soon as possible after 

 the early rains in October, November, and December, to a depth of from 7 to 

 10 in., harrowed or disked, and then cross plowed, the second plowing to be 

 followed also l)y harrowing. The pupa? are by this means broken from their 

 protecting cells and most of them either injured or killed. 



"A combination spray of black-leaf tobacco extract in the proportion of 1 part 

 of extract to 60 parts of water and 2 per cent distillate oil emulsion, or a spray 

 of bhick-leaf extract alone, should be used against the adults during early 

 March, just when the cluster buds begin to open, and against the larv* in April, 

 after the blossom petals fall. The thrips must be killed by contact insecticides, 

 and u)t by internal poisons. 

 15140— No. 8—09 5 



