THE AMERICAN ENTOMOLOGIST. 



43 



Colors— (a) liotwoon cream anil flesh colors; (ii) llesli 

 color; (c ami d) cream color, IjUick ami brown. 



tious ami stages of its existence; Figui-e ">i 

 h, h, of that of the bogus Colorado Potato- 

 bug. It will be seen at once that the head 

 of the former is black, that the first joint 

 behind the head is pale and edged with black 

 behind only, that there is a double row of 

 black spots along the side of the bodx', and that 

 the legs arc black. In the other larva (Fig. 34 h), 

 on the contrary, the head is of a pale color, the 

 first joint behind the head is tinged with dusky 

 and edged all round with black, there is but a 

 single row of black spots along the side of the 

 body, and the legs are pale. Take a hundred 

 fuU-groAVu specimens of tlic former larva, and 

 you will find them all to present the above char- 

 acters. Take a hundred full grown specimens 

 of the latter larva, and precisely the same rule 

 will hold good.* 



* We subjoin a teclmical ilcscription of the larva o£ Dory- 

 phorajuncta. That of the larva oi Doryphora 10-Uneala will- 

 be found in Dr. Fitch's N. r. Reports, Vol. Ill, pp. 231-i. 

 According to Dr. Fitch, the ground-color of this last larva is 

 ' 'pale yellow' ' in the mature state ; according to Dr. Shinier, 

 in his excellent article on the preparatory stages of this in- 

 sect, it is "orange." We oiu'selves should prefer to desig- 

 nate it as cream-color, more or less tinged with Venetian 

 red; and we think we have observed that the mature hirViiJof 

 the earlier broods are more strongly tinged with this color 

 than the mature larva; of the later hroods . • In the imm.ature 

 state the gi'ound-oolor of the larva is a dull Venetian red. 



DoHYPiiORA juxcTA, Germar; mature larva .—General 

 color a pale yellowish flesh-color. Head, with the .antenuaj 

 placed behind the hase of the mandibles, short and very ro- 

 bustly conical, three-jointed, joints 2 and 3 black. Precisely 

 as in W-Hneata, there are six small simple black eyes upon 

 each side, one pair longitudinally arranged and placed be- 

 low the antenna, the other two pairs arranged in a square 

 and xdaccd a little above and behind the antenna; tip of the 

 mandibles dusky. Lody, with the dorsum of joint 1 com- 

 posed of a separate transverse horny plate, rounded at the 

 sides, tinged more or less with dusky, and broadly edged 

 all round with black. Joints 1 — 3 each with a lateral horny 

 black tubercle, that of joint 1 placed below and behind the 

 horny prothoracic plate, and enclosing a spiracle. Joints 

 1—11 each with a similar lateral tubercle enclosing a spiracle ; 

 but the row composed of these eight tubercles is placed a 

 little above the row of thi-ec tubercles on joints 1 — 3, and the 

 last four of the eight are gradually smaller and sm,aller, 

 until that on joint Sis reduced to a simple black spir.acle; 

 dorsum of joints S and 9 dusky. Legs pale yellow; cox-u 

 exteriorly a little dusky, the two hinder pairs each more ami 

 more so, with a geminate horny plate above each, which is 



Now let us see what are the differences in the 

 perfect beetle state of these two insects, in which 

 state even a practised entomologist would, at 

 first sight, bo apt to confound them together. 

 Indeed, so minute are the differences, that in a 

 drawing of the natural size it is scarcely possible to 

 exhibit them, and in order to do so we have been 

 compelled to greatly magnify the wing-case and 

 the leg of each species. Figure 33 d, d exhibits the 

 True Colorado Potato-bug ; Fig. 34 c the Bogus 

 Colorado Potato-bug, each of its natural size. 

 Fig. 33 e shows the left wing-case enlarged, 

 and Fig. 33 /an enlarged leg of the former ; Fig. 

 31 a the left wing-case enlarged, and Fig. 34 

 e an enlarged leg of the latter. On a close 

 inspection it will be perceived that in the for- 

 mer (Fig. 33 e) the boundary of each dark 

 stripe on the wing-cases, especialh' towards the 

 middle, is studded with confused and irregular 

 punctures, partly inside and partly outside the 

 edge of the dark stripe ; that it is the third and 

 fourth dark stripes, counting from the outside, 

 that are united behind ; and that in the leg both 

 the knees and the feet are black. In the latter 

 (Fig. 34 d),on the contrary, the dark stripes are 

 accurately edged by a single regular row of 

 punctures placed in a groove (stria) ; it is the 

 second and third stripes — not the third and 

 fourth — counting from the outside, that ai"e 

 united behind, the space between them being 

 almost always brown; and the leg is entirely 

 pale, except a black spot on the middle of the 

 front of the thigh. 



The spots on the thorax, in either of the 

 above two species, are normally eighteen in 

 number, arranged in the same very peculiar 

 pattern which may be seen boUi in Fig. 33 d, d and 

 in Fig. 34 c ; and preciselj' the same variations in 

 this complicated ijattern occur in either species. 

 These are certainly ver)' remarkable and sug- 

 gestive facts ; and the reader who desires to see 

 them more fully discussed is referred to a passage 

 ill a scientific paper, published in 1805, by the 

 senior editor.* 



After all these statements, it will not.be won- 

 dered at that several otherwise well qualified 

 observers have imagined that they had captui-ed 

 the true Colorado Potato-bug in Illinois long 

 previously to the year 18G4. Many such cases 

 have been carefully investigated, and in every 

 one of them it has turned out, upon examining 



more and more dusky in each successive pair . An exterior 

 dusky dot, or small spot, on the tip of the femur and of the 

 tibia. Tarsus small, onc-jointcil, dusky, and with a black 

 claw. 



» Proceedings of the Entomolorjical Society of Philadelphia, 

 Vol. VL, pp. 207-8, 



