434 BOARD OF AGRICULTURE. [Pub. Doc. 



some series the two species closely approach each other. 

 P. spinosus usually reaches a size not attained by serieventris. 

 In the latter species the antennte are generally spread over 

 with brown and the humeral angles are bluntly acute, not 

 produced into slender spines. In spinosus there is usually a 

 well-defined sinuation in rear of each spine. 



The life history of this species, as briefly given by Riley, 

 is as follows : — 



The eggs of P. spinosus . . . are bronze-colored, caldron- 

 shaped objects, with a convex lid, around which radiate fifteen or 

 sixteen white spines. They are attached side by side, in clusters 

 of a dozen or more, to leaves and other objects. . . . The young 

 bug is ovoid, shiny black, with some bright crimson about the 

 abdomen. In the full-grown larva . . . four yellowish spots 

 appear on the thorax, and the abdomen becomes more yellowish. 

 In the so-called pupa, distinguished by wing-pads, the ochre yellow 

 extends still more, and in the perfect insect the black entirely dis- 

 appears. In the immature stages the shoulders are rounded, not 

 pointed ; the antennae are four-jointed instead of five-jointed as 

 in the adult, and the feet or tarsi have but two joints instead of 

 three. 



The diet of the young seems to be principally vegetarian, but 

 we have mentioned elsewhere (Fourth Rep. Ins. Mo., p. 20) 

 instances where the larva has been seen to destroy larvae of the 

 Colorado Potato beetle four or five times its own size. (Fourth 

 Rep. U. S. Ent. Com., p. 98.) 



At the time the Colorado potato beetle was spreading east- 

 ward, P. spinosus was perhaps its most frequently observed 

 insect enemy, as is shown by its frequent mention in articles 

 on the subject appearing at that time, and its services in 

 destroying this beetle were of sufficient value to call out 

 the commendation of many entomologists. In destroying 

 the cotton worm (Aletia argillacea) Riley rates this bug as 

 " the most abundant and effective " of the Heteroptera known 

 to attack the insect. The full list of insects which P. spinosus 

 is known to attack is given below : — 



Diapheromera femorata Say (Riley, Rep. U. S. Dep. Agr., 

 1878, p. 245), Coccinella sp. ? (Walsh, Amer. Ent., 1869, 

 vol. I., p. 13), Crioceris asparagi Linn. (Chittenden, Year 

 Book U. S. Dep. Agr., 1896, p. 346), Doryphora decern- 



