868 EXPERIMENT STATION RECORD. 



in April attacked the foliage of various plants, .such as Le Conte pears, 

 Kelsey plums, English peas, parsley, and endive. The damage to the 

 flowers of the strawberry was not so severe as in 1897, but blackberries, 

 dewberries, and roses suffered considerably more. 



The life history and habits of the insect were studied, from which it 

 appears that the life cycle of Thrips tritici is quite short, requiring but 

 12 days. The eggs are deposited in the tissues of the infested plants 

 and hatch in 3 days. The larval stage lasts about 5 days, during which 

 time the insect makes 2 molts. The nymph stage continues for about 

 4 days, in which time no food is taken. 



In 1897-98 experiments were conducted with a number of insecti- 

 cides for the control of this pest, and while a number of them proved 

 valuable, the laboratory experiments showed that rose-leaf insecti- 

 cide, whale-oil soap, kerosene emulsion, pyrethrum powder, and Ham- 

 mond's thrips juice were all efficient in destroying the insect under 

 laboratory conditions. For field purposes the most successful insecti- 

 cides are rose-leaf insecticide, whale-oil soap, and kerosene emulsion, 

 but on such fruits as the strawberry, blackberry, etc., the author 

 recommends the use of the rose leaf insecticide, since the oils present 

 in the other 2 give a disagreeable flavor to the fruit. 



During the spring seasons of 1897 and 1898 Thrips tabaci has proved 

 very destructive to onions, cauliflower, and cabbage in the vicinity of 

 Lake City. These insects were first noted about the middle of April, 

 when they were observed to be infesting onions in the station gardens, 

 and continued their destruction until about July 1, when they gradually 

 disappeared. This species is injurious to the foliage of many plants. 

 On onions it chafes the epidermis of the green leaves, causing them to 

 dry out, whiten, and frequently die. On cabbage and cauliflower the 

 effects are about the same. The life history and habits of this insect 

 show that it has a somewhat longer life cycle than that of T. tritici, 

 requiring about 1(5 days for its completion. This insect goes through 

 3 molts during its life cycle. The egg state lasts about 4 days, the 

 larval stage 8 days, and the nymph stage 4 days. 



This species of thrips can be successfully combated by the use of the 

 same insecticides as recommended for the previous species except that 

 the solutions should be somewhat stronger. 



Report on the San Jose scale in Maryland and remedies for its 

 suppression and control, W. G. Johnson (Maryland Sta. Bui. 57, 

 pp. 116, figs. 23). — Preliminary to a discussion of the Sau Jose scale, 

 the author reviews the entomological work of 1890 and 1897 and gives 

 an extended account of the introduction, present condition, distribu- 

 bution, and life history of the Sau Jose scale. The operations con- 

 ducted in Maryland for destroying the insect and preventing its further 

 introduction are given at considerable length. Fumigation with hydro- 

 cyanic-acid gas is considered the most successful treatment. Experi- 

 ments with whale-oil and other kinds of soap and kerosene are reported 

 upon and the result of their application in Maryland is stated. 



