359 



and Japanese plums are very little infested, while hawthorns in a few, 

 apparently exceptional, cases have been severely attacked. The 

 foUage of badly infested trees becomes covered with numerous fine 

 whitish blotches, very noticeable on the upper surface, which after a 

 time turn brown. T. pilosus has been found in most of the fruit 

 districts of Ontario ; that it has not been recorded before appears 

 to have been due to its close resemblance to the common T. biinaculatus. 



Jack (R. W.). Some Injurious Caterpillars. — Rhodesia Agric. JL, 

 Salisbury, xii, no. 1, February 1915, pp. 43-57, 3 plates. 



Laphycjma exempla, the swarming caterpillar, is a native of Africa, 

 and appears periodically. It was abundant in Umtali and SaUsbury 

 in 1910 ; in April 1914, it was again observed at the Experiment 

 Station, Sahsbury. In December 1914, serious damage to maize 

 crops was reported from Hartley, Mazoe, and Makoni districts. The 

 hfe-history has not been fully investigated. The eggs are laid in 

 clumps of about 60 oji the food-plant ; the caterpillars feed rapidly, 

 and having attained their full gro\\'th in a few weeks, enter the soil 

 to pupate. The adult emerges in two or three weeks and lays eggs 

 for the next generation. The natural food-plants are various grasses, 

 and this is the reason why the species is not usually in evidence, except 

 when it swarms from the veld on to the cultivated lands. It has been 

 recorded on maize, kafiir com, millet, oats, barley and wheat, and 

 occasionally on potatoes. The causes which lead to seasons of great 

 abundance are imperfectly understood, but can be summed up as the 

 concurrence of a number of favourable factors. The most active 

 checks are parasites, insectivorous birds and insects. Small numbers 

 of a parasitic Tachinid have been bred from this species. Parasitic 

 wasps play a similar part, and the white stork, Ciconia alba, kills great 

 numbers when the insect is abundant. Invasions are so rapid that 

 prompt measures are necessary ; the grass between the swarm and 

 the crop may be sprayed with poisoned sugar solution, consisting of : — 

 arsenite of soda, 1 lb. ; black sugar, 8 lb. ; water, 10 gals. Live- 

 stock must be kept off the treated veld. WTiere the catei-pillars 

 develop on the crop itself, nothing can be done if they are evenly 

 distributed, as maize and small cereals will not bear the cost of spraying. 

 If an intense attack occurs on a limited area, it is best to spray with 

 arsenite of lime, adding 3 lb. of black sugar to each 50 gals, of water. 



Laphygma exigua, the pigweed caterpillar, has been found in great 

 abundance on the pigweed, Amaranlhus paniculatus. This moth is 

 less restricted than the preceding in regard to its food-plants. The 

 eggs are laid in clumps on the food-plants. The caterpillars, which 

 hatch out in four days, feed rapidly, enter the soil in 18 days to pupate, 

 and emerge as adults 12 days later. Several generations follow 

 each other rapidly. In America, this species is said to pass the winter 

 as an imago ; in Rhodesia, moths emerge at least xmU\ late i]i June 

 and eggs are laid as early as September. The food-plants are lucerne, 

 potato, tobacco, swede, maize, spinach and mangold ; in the Trans- 

 vaal it has been reported on cotton, in the United States on pea, apple, 

 pear, onions and sugar-beet. As a pest in Southern Rhodesia, it is 

 chiefly connected with early potatoes gi'o\Mi in October ajid mangolds 

 in February and March. The best remedy is spraying with arsenical 



