375 



suspending fruit in a jar containing adults, after the latter have begun 

 to mate. It the eggs are to be closely observed, they should be 

 removed from the fruit and spread upon a firm leaf. The leaf is 

 inserted in a small tube, a cotton plug added to force the leaf to the 

 bottom, and the whole inverted and partially submerged in water. 

 An ordinary moist chamber is not so successful. The length of the 

 egg stage varies from 2-7 days at temperatures ranging from 78-9°- 

 62° F. The larvae pass through three instars. The length of larval 

 hfe varies from 6-14 days and seems to be influenced by the food. 

 Citrus fruits are not suitable for rearing work with either flies or the 

 egg-parasites. Adults should not be permitted to lay more than 150 

 eggs in such fruits as the apple, as overinfested fruits decay too rapidly. 



Patch (E. M.). Two Clover Aphids. —J I. Agric. Research, Washington^ 

 D.C., iii, no. 5, 15th February 1915, pp. 431-433, 3 figs. 



Aphis brevis, Sanderson, the long-beaked clover aphid, has been 

 found attacking leaves of Crataegus sp., and Cydonia japonica, the 

 Japanese quince. During the month of June the leaves are swollen 

 and curled and have a dark purple colour ; in late June and July, 

 the Aphid leaves the hawthorn, returning late in the season for the 

 sexual generation. Autumn migrants have been obtained from 

 Prunus sp., but no spring collections have been made from that host. 

 In the transfer tests carried out in 1912 migrants placed on alsike 

 and white clover fed satisfactorily and produced nymphs. Somewhat 

 later, colonies of the Apliid were found to have infested the bases of 

 Lathy r us odoratus growing near a hawthorn. Aphis bakeri, Cowen, 

 the short-beaked clover aphid, reported on T rifolium p)ratense at Orono, 

 Maine, is distinguished from the above species by the character of the 

 antennae. It generally occurs on the ventral side of the leaf and the 

 stem near the ground. Specimens have also been taken from hawthorn, 

 apple and shepherd's purse. 



DucKETT (A. B.). Para-dichlorobenzene as an Insect Fumigant. — 



U.S.Depl.Agric, Washinr/tou. D.C., Bull. no. 167, 10th February 

 1915, 7 pp., 2 figs. 1 table. 



The insecticidal value of para-dichlorobenzene as a fumigant, its 

 effect, if any, on cloth fabrics and the action of the vapour on plant 

 hfe, are discussed. This compound has only recently been used as an 

 insecticide ; it is a colourless, crystalline substance, volatilising very 

 readily as a colourless vapour with a peculiar ether-like odour. The 

 vapour is harmless to human beings and domestic animals under 

 ordinary conditions, but in many instances it is poisonous to insects. 

 The greatest advantages which it possesses over other fumigauts, are 

 its absolute non-inflannnabihty and its comparatively low cost to 

 purchase or apply, in proportion to the result obtained. Dr. Curschman 

 has concluded that para-dichlorobenzene is harmful to human beings 

 only in cases of internal application of large quantities, from 30-40 

 grains. As an insecticide, it is effective only where its vapour can be 

 confined, and at a temperature greater than 74° F. ; it is recommended 

 only where poison bait and contact sprays are undesirable. The 



