508 



have led to the tabulation of .species favourable or unfavourable to 

 the different stages of the life-history. Experiments to determine 

 the increase of the moth have shown that the introduction of parasites 

 has already had definite results. Dispersion seems to be due to the 

 carrying of egg-clusters on timber, etc., or to the spreading of the adults 

 by wind. Secondary insects are important in that they prevent the 

 recovery of many trees which would otherwise gradually recover. 

 Damage to forest trees cannot be controlled by hand methods such as- 

 are possible in the case of fruit or ornamental trees. In Europe, the 

 problem has been partly solved by growing species not susceptible 

 to attack. Investigations on the feeding habits indicate that the work 

 of eliminating the most susceptible trees is hkely to have good results. 

 A survey of the county of Middlesex in Massachusetts has been made 

 in order to obtain information concerning the distribution of the 

 various kinds of timber. Scouting operations carried out in various 

 localities have consisted in examining the territory along the outside 

 border of infestation and in treating colonies adjacent to the border 

 for the purpose of preventing spread of the insect to other parts. 

 Spraying work during the summer has given satisfactory results. 

 Quarantine work has been confined to infested regions in New England 

 and New York. The object of the work is to prevent egg-clusters or 

 larvae of the gipsy moth, or winter webs of the brown-tail moth, from 

 being carried out of infested regions. 



QuAiNTANCE (A. L.). The Apple Tree Tent Caterpillar. — V. S. Dept. 

 Agric, Washington, B.C., Bull. no. 662, 11th May 1915, 10 pp. 

 7 figs. 



The tent caterpillar {Malacosoma americana) is a native American 

 species occurring generally in the United States from Canada south 

 to Florida and west to the Rocky mountains. It usually feeds on the 

 wild cherry, which is probably its native food-plant. In the absence 

 of this, it attacks apple, plum, peach, elm, etc., often completely 

 defoliating the trees. Eggs are deposited in early summer, in masses 

 encircling the smaller twigs. The larvae, though they begin to develop 

 the same year, do not hatch till the following spring. Nests of silk 

 are formed on the leaves of the host plant and in these the larvae take 

 shelter during the early stages. Pupation takes place in any protected 

 place, under loose bark, etc., the cocoons usually occurring singly. 

 This species is subject to attack by numerous parasites and predaceous 

 insects, Calosoma scndator being the most important of the latter. 

 The caterpillars are also subject to a bacterial disease. Among the 

 methods of control are the collection of eggs, destruction of larvae, 

 removal of useless, infested trees, and spraying with arsenicals. The 

 collection of egg-masses is quite practicable when the leaves are absent ; 

 the twigs bearing them should be cut off and burned. Nests con- 

 taining the larvae may be removed by hand, or if present on the smaller 

 twigs, may be burnt out with an asbestos torch. Any arsenical 

 insecticide may be used : Paris green or Scheele's green in the propor- 

 tion of 1 lb. to 150-200 U.S. gals, of water, or lead arsenate at the rate 

 of 2 lb. to 50 gals, water, with 2 lb. of slaked lime, have been found 

 effective. Preferably, the poisons should be used in dilute lime-sulphur 



