76 Observations on Insecls (tffedlnr) the Turnip Crops. 



The ApJiLS-llon, or larva of the Golden-eye fly, destroys the 

 aphides; and \\\e maggots of some two-winged flies called Syrphi 

 arc still more serviceable in their destruction. 



These are^ however^ in their turn infested with a parasite called 

 Cerajjhron syrjjhi. 



Severe frosts destroy the aphides^ but they are able to propa- 

 gate in mild winters. 



When immersed in ivatcr for sixteen hours^ it has not killed 

 them. 



An atmosphere strongly im2:>regnated with camphor did not 

 affect them in twenty-four hours. 



The Turnip- LEAF miners may generate diseases in cattle, 

 when they greatly abound. 



One called Drosophila flava causes large blisters on the upper 

 sides of the leaves, which contain the maggots. 



The other, named Fhytomyza nigrico7mis, is the parent of a 

 maggot which eats galleries in the under-sides of the leaves. 



The Turnip diamond-back moth : the larvae feed upon the 

 turnip-leaves, and sometimes nothing but the fibres are left. 



l^lie chrysalis is inclosed in a net-work cocoon, attached to the 

 dried fibres, or formed upon the ground. 



It is found all over Europe from Midsummer to November, 

 and does great mischief in the kitchen-gardens in the Mauritius. 



Upwards of 240 of the caterpillars have been found upon one 

 plant. 



A parasitic Ichneumon lays its eggs in the caterpillars. 



The Y-MOTH lays its eggs on the under-side of turnip-leaves 

 and other plants. 



The green caterpillar feeds upon the turnip-leaves and a variety 

 of plants. 



The chrysalis is inclosed in a white web, often spun in the 

 folds of the leaves. 



The 7?ioths are abundant from April till October, especially in 

 the latter month and in July. 



Rainy seasons seem to be congenial to their increase. 



In October, 1816, the moths swarmed in the north of 

 France. 



In 1735, the caterpillars ate up all the vegetables around 

 Paris, excepting lentils. 



Their ravages extended to the centre and south of France, 

 where they consumed the hemjj-crops, and did not refuse grasses 

 and clover. 



They spared the corn-crops, but attacked the oats later in the 

 season. 



The previous ivinier and spring had been very mild. 



One female Y-mothin the spring might become the progenitor 



