432 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 



perforated to some extent. The adults, which dy from tree to tree, appeared plenti- 

 ful without much interruption throughout the season, and often several could be seen 

 feeding on each tree. Possibly many of these may have become poisoned before de- 

 positing the eggs. 



"The efficiency of London purple being established, it will generally be preferred 

 to other arsenicals, because of its cheapness, better diflfusibility, visibility on the foli- 

 age, etc. As the eftects of the poisons commonly do not appear decidedly for two or 

 three days after their administration, the importance of the preventive method of 

 poisoning in advance can not be too strongly urged. As the effect is slow in appear- 

 ing, impatient parties will be apt to repoison on the second or third day, and thus 

 put on enough to hurt the plant when the effect does come. Much depends on dry- 

 ness or wetness of the weather; but good effects may be expected by the third or 

 fourth day." 



In the same report is figured (Plate VI) a simple apparatus which was used to good 

 effect in spraying the trees and which was explained in detail in the text (pp. 168, 

 169). It is in brief a barrel pump containing a stirrer-bar, attached by a loop to the 

 swinging end of the pump, and which by its oscillations constantly stirs the mixture. 

 The barrel rests upon a skid in the bottom of a light cart in which it is drawn from 

 tree to tree. To the nose of the pump is attached a long, slender rubber hose. To 

 enable the operator to thrust the hose up among the branches of the tree, it is run 

 through a long bamboo pole the septa of which have been burned out by a hot iron 

 rod. At the end of the hose is a short metallic rod to which one of the cyclonic or 

 eddy- chambered nozzles has been attached. 



By the use of such an apparatus, which is comparatively inexpensive, a great many 

 trees can be thoroughly sprayed in the course of a day. Such a course requires labor 

 and some expense, but the result can be accomplished in no easier way. 



We have already given the general appearance of the egg, and the larva will be 

 readily recognized from the figure (158). It is practically indistinguishable from the 

 larva of the closely allied Lina lapponica which feeds upon willow at the North, but 

 the larva of the latter species emits the milky fluid more freely and has perhaps a 

 more pungent odor. We published in the American Entomologist, Vol. Ill, p. 160 

 (July 1880), a detailed description of the larva, which it will be unnecessary to repeat 

 here. 



The beetle is extremely variable in its coloration, and it may not be amiss in this 

 place to repeat in connection with fig. 157, for purposes of identification, the descrip- 

 tions which we have given {ibid.) of certain of the more marked varieties. Com- 

 binations, however, in many degrees, of these varieties occur. 



a. Typical. Black, with a tinge of blue; basal jointsofantennse beneath, thickened 



thoracic margin with exception of a small round spot at the middle, elytra with 

 exception of suture and three lines of interrupted black markings, base of fe- 

 mora and part of tibiae, and sides and apex of abdomen, testaceous yellow. 

 (Common at the West.) 



b. Variations in general coloration : 



1. Base of antennae, head, underside, and legs of the same yellowish color as upper 



side. (From Texas.) 

 a. Thorax testaceous-yellow, or more reddish, with the two lateral markings 



and a 2^ shaped mark on the disk blackish, 

 /3. Thorax entirely testaceous-yellow. 



2. Principal color above and beneath blue ; legs blue. 



y. Sides of thorax as in typical form. Elytra with faint yellow marking. (From 

 California.) 



d. Sides of thorax as in typical form. Elytra unicolorous blue. (From California.) 



e. Entirely blue, except a narrow lateral yellowish marking each side on the last 

 abdominal joint. 



