THE COLEOPTERA 



107 



unless the tree is vigorous, in which case such an outpouring of sap may 

 occur at the wound as to kill (drown?) it or drive it into the outer layers 

 of bark where it may live for a time, later working back into the sap-wood 

 if the flow becomes small enough to permit it. If the larva can feed in 

 the sap-wood it will grow to full size, about an inch long, by fall, at this 

 time burrowing into the wood to form a pupal cavity in which the winter 

 is spent, pupation itself taking place there the following spring and con- 

 tinuing several (throe to four) weeks, after which the adult beetle escapes. 



FIG. 96. Flat-headed Apple-tree Borers (lance) of various sizes. Natural size. (From 

 U. S. D. A. Farm. Bull. 1065.) 



Control. Vigorous, healthy trees are not generally liable to attack, 

 and cultural methods which will insure this condition are important. 

 Trees headed low will shade their trunks and the sun-loving beetles will 

 go to those exposed to sunlight. Shading trunks exposed to the sunlight, 

 by boards cutting off this light, is a protection, as are also poles set in 

 the orchard and covered with sticky material to catch and hold the beetles 

 visiting them in search of places to lay their eggs. Wrappings of burlap 

 or paper extending from the ground to the limbs will prevent egg-laying, 

 but should be removed when this period is past. Birds and insect enemies 

 aid in controlling this pest. 



Family Elateridae (Snapping beetles; click-beetles; skip-jacks). 

 These insects somewhat resemble the Buprestids when adult but are 

 usually more slender, with their sides more nearly parallel, and the 

 economic species also lack a metallic reflection. The hinder corners of 

 the pronotum are elongated forming sharp points in the majority of the 

 . group, and the insects are usually some shade of brown or black f though 

 the pronotum and elytra sometimes differ in color and the latter are 

 spotted in some cases, mottled black and white in our largest common 

 species, and some have rather bright colors or markings (Figs. 97 and 98). 

 When these insects fall on their backs they are able to throw themselves 



