356 



combinations of fertilisers experimented with cannot be depended 

 upon to protect narcissus against infestation by eelworm. Experi- 

 ments in chemical sterilisation of the soil with such substances as gas- 

 lime, calcium carbide, naphthaline, carbon-bisulphide, toluol, formalde- 

 hyde and ammonia, indicate that this treatment cannot be depended 

 upon to free the soil from eelworm. Finally, experiments were made 

 to determine whether crops liable to attack by this eelworm could be 

 sown with safety on land that had carried diseased bulbs. Rye, 

 winter and -spring oats, clover, lucerne, peas, broad beans, rye-grass, 

 onions, wheat, chives, buckwheat and potatoes, were all sown on 

 infested land, Tylenchus devastatrix having been recorded on all these 

 food-plants. The plants were examined from the seedling stage 

 onward throughout the growing season, and, except in the case of 

 onions, the various crops were unaffected. These results clearly 

 show that onions should not follow in immediate succession on land 

 that has borne a diseased crop of narcissus. The behaviour of the 

 other crops confirms the theory previously postulated by Ritzema 

 Bos [see this Review, Ser. A, v, p. 441], that T. devastatrix becomes 

 so adapted to a particular species of food-plant that it will not attack 

 any other species with any severity. Experiments were also conducted 

 in which pots of sterilised soil were sown with the above-mentioned 

 plants, the pots being watered once with water containing eelworms 

 grown in pure culture. In this case, onions were again the only plants 

 affected. 



Fletcher (T. B.). Agricultural Entomology.— Reprint from Ann. 

 Rept. Bd. Scientific Advice for India, 1917-18; Calcutta, 26th April 

 1919, 15 pp. [Received 23rd June 1919.] 



The information contained in this report has been*previously noticed 

 [see this Review, Ser. A, vii , p. 132]. 



Metcalf (C. L.). Eumerus strigatus again (Dip., Syrphidae). — Entom. 

 News, Philadelphia, xxx, no. 6, June 1919, pp. 170-174. 



Previous records of the occurrence of Eumerus strigatus are reviewed ; 

 the first published report of this fly from America seems to have been 

 in 1910. There are said to be two generations in a year ; the food- 

 plants include onion, iris, shallot, narcissus, hyacinth, and Amaryllis. 

 It is apparently thoroughly established in widely separated regions of 

 North America, as is another Syrphid, Merodon equestris (larger 

 narcissus or daffodil fly). The author considers that it constitutes a 

 real and unappreciated menace, and that the probability is that there 

 will be a sudden and severe outbreak of one or both of these pests 

 when they are more thoroughly acclimatised and experience a period 

 of conditions favourable to their rapid increase. M. equestris passes 

 six months hi the larval stage, pupating in the soil in February and 

 the adults emerging in late March and ovipositing in May. The food- 

 plants recorded for this species are : arcissus, Amaryllis, Vallota, 

 Hahranthus, Eurycles, Galtonia, and the wild hyacinth, ScUla nutans. 

 Remedial measures suggested are the examination of all bulbs to be 

 planted and the destruction of all infested ones. Bulbs may be partly 

 freed from infestation by submerging them from two to eight days and 



