68 Belladonna Leaf-Miner 



are drenched. It penetrates the epiderm where the latter has become 

 detached from the parenchyma and is most effective against the larvae 

 of the younger stages. The best results are achieved if the nicotine- 

 paraffin-emulsion is delivered to the plants just before the flies may be 

 expected to oviposit as it wards off the adults. Frequent sprayings 

 should be made in order to keep the pest under control. The cost works 

 out at about 3s. ^d. per 100 gallons of the mixture. 



11. Natural Enemies of the Belladonna Leaf- Miner. 



Three species of parasitic Hymenoptera were reared from the puparia 

 of hyoscyami. Of these two are Braconids belonging to the genus 

 Opius and one of them is Opiiis nitidulator Nees ; PI. I, fig. 23 represents 



Fig. 4. Opius nitidulator Nees. Parasite of Pegomyia hyoscyami. Also parasitised 

 puparia of Pegomyia showing the ragged edges where t}ie parasites have emerged. 



the fully developed larva of the latter dissected out from the puparium 

 of its host. The third is a Proctotrypid, probably a hyperparasite of 

 one or other of the two species of Opius, or perhaps of both. It was com- 

 paratively rare. The percentage of parasitism is rather high and, as 

 the season advances, increases in intensity until the beginning of Sep- 

 tember, when it suffers a diminution. 



Examination of larvae and puparia collected towards the end of 

 this month and during October revealed very few parasites, a fact which 

 may be associated with the diminution in temperature experienced in 

 the autumn. This is borne out by the fact that the parasites are not so 



