266 



spring. The longest pupal stage observed in the laboratory under 

 natural temperatures was 45 days, the shortest 8 days. The adult 

 escapes by gnawing its way through the seed-pod. Under favourable 

 conditions about 30 days are required for the complete development of 

 each generation, of which in California there are probably three in one 

 season. Liodontomerus secundus, Gah., another parasite of the larvae 

 of B. funebris, has been previously described [see this Review, Ser. A, 

 V, p. 405]. The parasitic larvae hibernate within the seed destroyed 

 by their host. The pupal stage lasts 24-40 days in April, May and 

 June, and the adults emerge in the spring, some having been noticed 

 as late as July. There are probably two or more generations in a 

 season. 



The Pteromalid, Eutelus brucJiojjliagi, Gah., hibernates in the larval 

 stage. In the spring pupation is short, and the adults escape by 

 gnawing through the seed wall, their life lasting one or two months. 

 There are probably at least two generations in one season. 



The larva and pupa of another Pteromalid, T rimer omicrus maculatus, 

 Gah., are described, this parasite hibernating as early as September 

 in the larval stage within the lucerne seed. Pupation takes place in 

 the spring, the adults emerging from the seeds by the time the new 

 pods are forming. The larva attaches itself to that of its host, which 

 dies in the course of a few days, the parasite growing rapidly while 

 feeding on the dead host. The longest pupal period observed was 

 15 days and the shortest 6 days. 



Frost (S. W.). Two Species of Pegomyia mining the Leaves of Dock. 

 — Jl. Agric. Research, Washington, D.G., xvi, no. 9, 3rd March 

 1919, pp. 229-244, 3 plates, 1 fig. 



Pegomyia calyjitrata, Zett., is a common leaf-mining Anthomyid in 

 America, but is very rare in Europe. It is believed that this fly feeds 

 solely on Rumex spp., as attempts to rear the larvae on any other 

 food-plant all failed. The eggs are laid in nature in groups of 3-5 

 or more on the under-surface of the leaf. The incubation period 

 varies from 2 to 6 days, the young larvae immediately entering the 

 leaf. The larval stage depends greatly on weather conditions, but 

 averages from 9 to 15 days. On reaching maturity the lar\^ae fall to 

 the ground and penetrate the soil to a depth of 2 or 3 inches, where they 

 pupate ; if the soil is too hard, pupation takes place under fallen 

 leaves or rubbish. The duration of the adult life is uncertain, as also 

 is the number of generations in the year. From the puparia of 

 P. calyptrata the parasites, Opius quebecensis, Prov., and Dacnusa 

 scaptomyzae, Gah., were reared, and the eggs were found parasitised 

 by Trichogramma minuium, Kiley. An adult and nymph of the bug, 

 Nabis ferus, L. , were seen attacking the larva. 



Pegomyia affinis, Stein, is much less common than P. calyptrata. 

 The eggs are laid in the same way, but are less abundant. The incuba- 

 tion period is 3-7 days, and the larval stage varies from 12 to 18 days. 

 This species also feeds exclusively on Rumex spp. There are probably 

 only two generations a year, pupation taking place as in P. calyptrata. 

 The early stages are described, and a comparative table of the 

 characters of the two species is given. 



