186 



parasitises the woolly aphis [E^-Zoso^irt lanigeritrn], and a shipment of 

 the parasitised Aphids has reached Capetown. 



During November outbreaks of locust hoppers occurred in various 

 districts. In the Transvaal a reported outbreak was found to be due 

 to a remarkable abundance of immature grasshoppers so closely 

 resembling the true locust hoppers that experienced officers at first 

 sight mistook them for the latter ; no similar case has ever before 

 come to the notice of the division. 



VAN DER Mervve (C. P.). The Tobacco Slug {Lema hilineata. Germ.). 

 — //. Dept. Agric, Union S. Africa, Pretoria, ii, no. 1, Januarv 

 1921, pp. 28-38, 3 figs. 



Until recently tobacco has been considered to be free from serious 

 pests in the field in South Africa, probably because no plants of its 

 genus are indigenous there. A potentially serious pest has now 

 appeared in the form of a South .\merican Chrysomelid beetle, Lema 

 bilineata, Germ., probably introduced during the South xVfrican War, 

 when large quantities of forage, etc., were imported from Argentina. 



The first record of its presence was made in 1911 at the Cedara 

 Agricultural School, Natal, and it was first observed by the author in 

 Durban in 1916, feeding on Physalis lobata, an introduced plant and a 

 common weed. 



The lower leaves of tobacco in the field are the first to be attacked. 

 The eggs are laid almost invariably on the under-sides of the leaves 

 in close masses of 15-20. At first the larvae are gregarious and 

 attack only the lower surface of the leaf ; later they separate, and 

 eat large ragged holes through the leaf. If many are present, only 

 the midribs are left. In some places the plants, both in the seed- 

 beds and in the fields, have been completely destroyed. Tobacco in 

 the curing sheds, and even in bales, is also attacked, but this only 

 occurs while it is still green. 



Where it is customary to cut the whole plant and hang it up in the 

 shed, drying takes more than a month, and larvae brought in on the 

 plant have time to mature. The damage done in the sheds is therefore 

 very great ; it can be prevented by other methods of drying, but 

 should be trifling if proper remedies are applied in the field. 



Observations indicate that the latest date for oviposition is about 

 the end of March. At Durban the period during which the beetles 

 did not feed was found to be about four months. Eggs were found 

 again from 4th September, and beetles were observed to be feeding 

 two days before. The egg-stage lasts four to seven days at Durban, 

 or even less at midsummer. The greatest number of eggs obtained 

 from one female was 2,421, with an average of 1,225. The egg-laying 

 period lasted from 15 to 124 days, with an average of 65, exclusive 

 of the period of hibernation. The larva moults three times, the last 

 moult being when it is six to ten days old. It pupates two to four 

 days later. From 10 to 19 days elapse between entrance into the 

 ground for pupation and emergence of the adult, the full cycle from 

 the egg to the adult varying from 17 to 30 days. As a rule the adults 

 are comparatively long-lived, hibernated females surviving from 

 194 to 284 days, with an average of 230. Though no males have been 

 kept alive through the winter, it is believed that some hibernate. 

 Paired females may hibernate, and without again mating, lay 

 fertile eggs, being thus able to set up new centres of infestation. 



