THE COLORADO POTATO-BEETLE. 
149 
some cases. They and their larvae are said to possess poisonous 
properties which have been known to affect people handling 
them, and to produce serious illness in those who have inhaled 
the vapours given off during the operation of scalding large 
quantities of the larvae, or burning potato-haulms infested by 
them. Even the birds and domestic poultry were said at first 
to refuse to eat them ; and in one Beport we are told that the 
prairie hens alone would touch them, but that the flesh of the 
birds was rendered so unwholesome by this diet that it could no 
longer be eaten with impunity. We may suspect some exagge- 
ration in these statements, especially as we find at a later period 
of the visitation that several farmers found their fowls feed 
freely upon the larvse, and even recommended the cooping of 
chickens in the potato-fields as a means of checking the pest. 
Other birds also have probably accustomed themselves by this 
time to the taste of this novel food ; at least, it has been ob- 
served in some parts of Iowa that the rose-breasted grosbeak 
( Guiraca ludoviciana) feeds freely upon the larvae, and 
although this bird was formerly rather rare, it has now become 
plentiful in the district. 
But if the birds have been inclined to fight shy of the 
western beetle, it has met with an abundance of insect foes in 
the course of its invasion. Among those which have rendered 
themselves prominent in this warfare, several species of lady- 
birds devour the eggs of the beetle ; a tiger-beetle ( Tetracha 
virginica ), and several Carabidae, eat the larvae ; a wasp ( Polistes 
rubiginosus) carries them off to its nest to furnish provisions 
for its young ; an Asilide fly {Promachus Bastardii ), and 
several species of true bugs ( Rhynchota ), especially a Har - 
pactor and an Arma, pierce the larvae with their beaks and 
suck out the juices ; whilst a Tachinide fly ( Lydella Dory- 
phorce , Biley) attacks them by the insidious method of parasit- 
ism, depositing an egg upon the surface of the larvae, generally 
near the head, the young parasite produced from which 
burrows into the body of the victim and feeds upon its sub- 
stance, not destroying it, however, until after it has descended 
to the ground when full grown. A long-legged spider or 
harvest-man ( Phalangium dorsatum) is also described as 
feeding upon the larvae in some districts ; and the beetle has 
been found infested with adhering mites like those so con- 
stantly seen on our common dung-beetles ( Geotrupes ). 
From the published Beports it would seem that these insect- 
enemies of the potato-beetle being mostly natives of the soil, 
have exerted their powers of destruction so vigorously against 
the western invaders as to have greatly checked their multipli- 
cation, the numbers of the carnivorous species having increased 
with a rapidity proportionate to the abundance of nourishment 
