126 On the Life History of " Wireworms" 



of damage. Ten larvae of A. ohscurus were enclosed in a pot with plants 

 just above the ground. At the end of six weeks, no evidence of attack 

 could be found and the plants appeared in no wise inferior to those in 

 the control pot. Possibly the smaller rootlets may have been attacked, 

 but though the length of the larvae was doubled during the experiment, 

 the plants appeared quite healthy. 



The rate of growth of the young larvae in the first instar I have found 

 to be exceedingly slow, differing in this respect from the experience of 

 Adrianov. His specimens of A. lineatus, from a length of l-25-r75 mm. 

 at hatching, had obtained a length of about 4-5-5-0 mm. in eleven 

 weeks, while A. spufator, from 1-0-1-5 mm., had grown in a few cases 

 to 6 mm. or even more. As he points out, however, the total number of 

 specimens of the latter species examined was only small and he does 

 not regard them as typical. Other tables for the two species, reared 

 more nearly under field conditions, show A. lineatus on 25th September 

 (? 7th October by Western Calendar) to be of an average length of 

 4*3 mm. and of A. sputator 3-5 mm. 



As will be seen from the data given when dealing separately with 

 the two species, larvae of A. ohscurus and A. sputator were in general 

 found to be larger than Adrianov's at the time of hatching (2-2-75 mm. 

 for A. ohscurus, 1-2-5 mm. for A. sputator), while A. ohscurus barely 

 attained to the length given by Adrianov for A. sputator in September — 

 October of the year of hatching by the end of the first instar (in the 

 following June). 



Larval specimens of A. sputator from the 1916 brood have unfor- 

 tunately been few in number, but so far as the information gathered 

 from them goes, this species appears to keep pace with A. ohscurus in 

 rate of growth. At the end of twelve months, either species reaches little 

 beyond the maximum length of Adrianov's laboratory-fed specimens of 

 only eleven weeks' growth. Possibly A. lineatus may be of more rapid 

 growth than A . ohscurus, but the few laboratory-fed sputator of Adrianov 

 which reached so great a length as 6 mm. must be regarded as quite ex- 

 ceptional; though even the average (3-5 mm.) of the large number (44) 

 measured by him from his outdoor cultures considerably exceeded that 

 of either sputator or ohscurus in anything approaching a similar period at 

 Rothamsted. 



At the first ecdysis, which takes place in June, the larvae of 

 A. ohscurus had grown but little, but during the second instar their length 

 was about doubled. The second ecdysis occurs at the end of July and 

 in the beginning of August, so that growth at this point is rapid. After 



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