Turnip Flea-Beetle. 103 



from time to time, in the Entomological Magazine^ under the 

 signature of Rusticus, and who brought to the enquiry a 

 knowledge of the habits of insects, instituted a series of experi- 

 ments in order to ascertain whence the turnip beetle comes in 

 such numbers. He says that he had always observed that there 

 was the greatest quantity of grubs on very young plants, of very 

 various size; and that it was not till the plants were a fortnight 

 or three weeks old, that the beetles appeared in any numbers ; 

 yet that there were some beetles from the very first coming up of 

 the plant. He was next anxious to ascertain whence it happened 

 that there were such numbers of grubs covering the cotyledons, 

 and states his opinion that they must have sprung from eggs, 

 either left in the ground from the previous year, or laid on the 

 turnip seed itself, and harvested with it in the autumn. He then 

 details a series of experiments which led him, from their results, 

 to suppose that the eggs of the beetle are deposited upon the 

 seed of the turnip previously to its being harvested : indeed, he 

 discovered on the seed a number of white flattish substances, 

 which he concluded to be the eggs of the Haltica. Hence he 

 adopted the practice of steeping the seeds in brine sufficiently 

 strong to kill the supposed eggs, and yet not to injure the seed; 

 and he states, in conclusion, that the plan was attended with 

 very satisfactory success. In support of these statements, he 

 adduces several facts : 1st, That self-sown turnip seed is more 

 infested than that which is sown in the usual way ; 2dly, That, 

 when the seed is gathered in very hot dry seasons, the produce 

 is more infested than when the seed is harvested in wet and cold 

 seasons ; and, 3dly, That, on shaking the flowers of the turnips, 

 the perfect beetles are found amongst them. 



There were, however, ample reasons for doubting the correct- 

 ness of this view of the subject. The facts adduced in its sup- 

 port were unsatisfactory ; it having been proved that the appear- 

 ance of the insect was greatly influenced by the hotness or 

 wetness of the season, and that it was found in the perfect state 

 through the summer and autumn ; so that, from the circumstance 

 of its feeding throughout its perfect state upon the turnip, the 

 discovery of it amongst the flowers of that plant was no proof 

 of its intention to deposit its eggs upon the seed. But the fact 

 that the seed of the turnip is harvested before the pods have 

 burst open, is sufficient to show that the Halticaj cannot deposit 

 their eggs upon the enclosed seeds. Moreover, it is quite incon- 

 sistent with the economy of insect life, to suppose that an egg^ 

 the grub of which, when hatched, is destined to feed above 

 ground, should be placed by the parent insect in a situation 

 where it must necessarily be buried. Again, if the turnip fly 

 be produced, as Rusticus presumes, from eggs laid upon the 

 seeds, how did it happen that there were some beetles from the 



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