140' FOURTH ANNUAL REPORT OF 



and might with propriety be introduced in the section of " Beneficial In- 

 sects." It is never found in sound or green wood, but invariably in that 

 which is decaying; and it very materially assists and hastens the reduction 

 of stumps which might otherwise remain treble the length of time to occupy 

 valuable ground, and serve as an eye-sore,to the careful farmer in wooded 

 countries. Unseen and unheard it carries on incessantly the good work of 

 converting useless timber into mould which enriches the soil; and this has 

 been its office in all the past ages of its existence. A decaying, moist con- 

 dition of the wood is necessary to its development, and it will be found most 

 common on low moist ground, and in Oak, Hickory and Sweet gum logs or 

 stumps. 



Common as is this beetle, its larva and pujia are rarely seen, and seem 

 to be unknown even to most entomologists, while no good figures of them 

 have been published. 



The larva (Fig. 62, a) is of a ver}" exceptional character being the only 

 one in this country which possesses but four well developed legs, for though 

 man}'- butterflies in the imago state have the front pair functionally impo- 

 tent, no other insect than our Passalus exhibits a similar feature in the 

 larva state. Indeed the only other larva in the whole Class of Insects 

 Avhich ai'C similarly characterized, are those belonging to the same genus in 

 other parts of the world. The third pair of legs really exists, however, in 

 a rudimentary state, as shown at Figure 62, d. This larva is of a bluish- 

 white color with the anterior joints broader and flatter than the rest. It 

 transforms in the fall of the year, within the wood it inhabits, to a whitish 

 pupa (Fig. 62, b) in which the front pair of legs is thrown forward under the 

 head, and the horns of the future beetle show plainly on its toj). The pupa 

 lasts but about a fortnight, when, throwing off the pupal garb, it becomes a 

 perfect beetle. At first the parts are all beautifully white and delicate; 

 then the head, thorax and limbs gradually become amber-brown, and lastly 

 the wing-covers assume this color. The whole body then deepens very 

 gi"adually so that many days elapse before the coal-black color is acquired ; 

 and in the month of August the beetle is as often found brown as black. 

 As larvae only half grown are found in company with those that are full 

 grown, they require at least two years to mature. 



Passalus cornutus Fabr. — Larva — Color bluish- white, with a dark medio-dorsal line; polished, 

 with scarcely any hairs; 13 joints exclusive of head; slightly arched; the thoracic joints broader and 

 flatter than the rest [though in alcoholic specimens they often appear the reverse] ; joint 1 with a promi- 

 nent neck- wrinkle underneath, and with a slight horny depression each side above, the prominences 

 immediately outside of the depression being often marked with dark brown; abdominal joints, 4 — 11 

 inclusive, each with a broad, slightly elevated fold, occupying the hind Ji of the joint in the middle 

 of the back, gradually increasing until at the sides it occupies the whole width of joint; 13th or anal 

 joint, bulbous, as long or longer than any of the others; anus 'transverse, surrounded by triangular 

 folds. Head, except the parts mentioned below as dark brown, light rust-brown; rather small; 

 flattened above; smooth, with a few stiff lateral yellowish hairs springing from ocelli-like dots; an- 

 tennjB 3-jointed, the basal joint broad, short; 2nd only half as wide and about the same length; 3rd 

 brown, as long as 1 & 2 together and fusiform; epistoma large, transverse, divided in two by a brown 

 transverse line; labrum smaller, transverse-oval, and sparsely furnished with stiff, yellow hairs; 

 mandibles moderately large, with two sharp-pointed teeth at extremity and a larger single tooth in- 

 side; brown with the teeth black ; maxillae composed of a basal transverse piece, a stout cardinal 

 jjiece; two inner lobes, well separated, pointed and curved inwardly in the same direction as the 

 madibulary teeth and with their inner border fringed with stiff hairs; maxillary palpi 3-jointed, the 



