NO. II LARVAE OF THE ELATERID BEETLES — GLEN 43 



The typical aeripennis has been associated with damage to wheat in 

 the Peace River Block and is a pest, especially of truck crops, along 

 the Pacific coast and in the inland mountain valleys. In northern 

 Saskatchewan forests the larvae have been collected in moist sandy 

 soil just under the surface litter and have been associated with plant 

 injury when such areas have been brought under cultivation. 



The subspecies destructor is a major pest in fields (King, 1928, 

 pp. 702-703; King et al., 1940) and gardens (Glen and King, 1938; 

 Munro and Schifino, 1938), the larvae being most abundant in loam 

 or silty soil and in fields which have been cropped to grains or grasses 

 for 5 or more years without summer-fallowing. Irrigated land in 

 southern Alberta is less severely infested with this wireworm than is 

 unirrigated land. Although primarily phytophagous, the larvae have 

 been found attacking inactive stages of various insects including 

 prepupal larvae of the sugar-beet webworm, Loxostege sticticalis 

 Linnaeus, and egg pods of the grasshoppers Camnula pellucida 

 Scudder and Melanoplus spp. In captivity, cannibalism occurs if the 

 larvae are overcrowded. Strickland (1935, pp. 521-524; 1939; 1942) 

 discusses the biology of this species and reports the larval period as 

 varying from 3 to 10 years and the number of larval instars as rang- 

 ing from 10 to at least 24. Rearing studies conducted at the Saskatoon 

 laboratory have shown pupation to occur in the field from July ii to 

 August 8, most commonly in late July. Under laboratory conditions 

 the pupal period usually lasts from 2 to 3 weeks. The pupal chamber 

 is an unlined, irregular, earthern cell, commonly subovate, measur- 

 ing from 9 to 10 mm. l)y 18 to 22 mm.; usually it is formed within 

 3 inches of the soil surface. 



In addition to the primary features of the aeripennis group, the 

 most important characters for the identification of the larva of Lndius 

 aeripennis are: Ninth abdominal segment (figs. 6, d; y, a, d) withotit 

 setae on central dorsal area and with broad, rounded "teeth" {to) on 

 sides of dorsal plate, and abdominal mediotergites {mtg, fig. 6, a, c) 

 with transverse branches of impressions on second to eighth segments 

 reaching approximately one-third of distance from longitudinal 

 branches to middorsal suture. In structure, the two subspecies are 

 indistinguishable except by size. The typical aeripennis larva attains a 

 length of 27 or 28 mm. and a width of 3.75 mm. ; destructor rarely 

 exceeds 22 mm. in length and 3 mm. in breadth. The eastern North 

 American appropinquans (Randall) and the European aeneus (Lin- 

 naeus) are so similar that constant structural differences have not 

 been found and separation is most readily made on the basis of 

 distribution. 



