69 



after a certain date and also bv removing tlie tips of the shoots, 

 which prevents the formation of new bolls and flowers. Sheep and 

 goats can be advantageously grazed in standing cotton after the crop 

 is off and will destroy many of the old bolls left in the field. 



GuNN (D.). The Fig and Willow Borer {Phryneta spinator). — 

 Union of South Africa, Dept. Agric, Pretoria. Bull. 6, 13th June 

 1919, 22 pp., 16 figs. [Received 20th December, 1919.] 



The Longicorn beetle, Phryneta spinator, has for several years 

 caused serious damage to fig trees in the four Provinces of the TJnion, 

 as well as in Rhodesia, British East Africa, Nyasaland and the Belgian 

 Congo. A willow, Salix capensis, is probably its native food-plant, 

 but it also attacks apple, apricot, nectarine, peach, pear and plum, 

 as well as grape-vines, Melia azedarach, Cupresmis lusitanica and 

 C. horizontal is. 



The various stages are described. The female searches for a suitable 

 position on the bark of the stem, usually from about ^ an inch below 

 to 12 inches above the soil surface, on which she proceeds to make 

 a transverse, vertical or T-shaped slit. Below this a cavity is made 

 into which the eggs are inserted and covered with a gelatinous 

 substance. Usually only one egg is laid in each cavity, but if several 

 are deposited, the strongest larva generally develops cannibal habits 

 and devours the others. Under natural conditions in Pretoria, 

 oviposition occurs from the middle of November to about the middle 

 of March, each female depositing from 18 to 34 eggs. 



The eggs hatch in from 10 to 18 days. The emerging larvae feed 

 on the tissues surrounding the egg-slit. The chief damage is caused 

 by the subsequent borings of the larvae in the soft tissue, and these 

 by the end of the first summer have become a broad irregular, semi- 

 circular gallery beneath the bark. The presence of the pest is indicated 

 by the appearance of a yellowish brown dust and sticky exudation 

 at intervals on the stem of the tree. Trees may become completely 

 girdled and die, or if the injury is not sufficient to kill the tree, the 

 crop of figs gradually diminishes. 



The larvae are less active during the winter months than in the 

 summer. At the end of the first year the tunnels penetrate the hard 

 wood and usually are continued in a downward direction. The burrows 

 examined in 1917 varied from 1| to nearly 3 feet in length, 1 to Ih 

 inches in diameter and from 1 to If inches in depth. About June 

 the pupal cells are excavated, the process occupying from 3 to 4 

 months. After the completion of the pupal ceU 2 or 3 weeks may 

 elapse before pupation occurs. The larval period lasts about 32 

 to 34 months and the pupal stage from 8 to 21 Aveeks. The adult 

 remains for several days in the pupal cell before boring its way to the 

 exterior. The beetles seldom fly any distance from their native tree ; 

 they enaerge from the middle of November to the end of February 

 and gradually begin disappearing in March. In cage- experiments 

 the life of individuals varied from 172 to 207 days. The ratio of 

 females to males is thought to be about 3 to 1. The fig trees used 

 for these observations varied in age from about 6 to 15 years, and 

 it was noticed that the larval period is slightly shorter in the younger 

 trees. 



