THe HyMENopTerA OF MINNESOTA 203 
plant lice have been called “ants’ cows.” Because the ants in many 
cases act as nurses for plant lice, protecting them from harm in vari- 
ous ways, and encouraging their increase, they are indirectly injurious 
to the farmer, orchardist, and gardener. An orchardist who sees large 
numbers of ants on his trees, must not infer that they are themselves 
working injury to the tree. A careful search will doubtless disclose 
large numbers of plant lice. 
Ants are also associated with insects other than aphids. One finds 
in their burrows ants’ nest beetles (Pselaphidae and other families) 
also Hemiptera and Orthoptera. A few crustaceans also live with ants. 
Some of these aliens in ants’ nests are parasites, some are messmates. 
Of 1,177 species of insects recorded by Wasmann in 1900 as living for 
a part or all of their time in ant nests, 993 were beetles (Pselaphidae, 
Staphylinidae, Histeridae, Silphidae, etc.), 76 were Hemiptera (plant 
lice and scale insects ), 39 Hymenoptera, 26 Lepidoptera larvae, 20 Thy- 
sanura, 18 Diptera, 7 Orthoptera larvae, 34 mites and 20 spiders. 
Monomorium pharaonis is the tiny house ant introduced into this 
country from the Old World, barely visible, yet sometimes a great pest. 
To be successful in eradicating it from a house, it is necessary to 
destroy not only the workers of the colony but the queen or queens. 
This is sometimes accomplished by means of fumigation. So tiny are 
these insects that it requires “17,000 individuals to weigh one gram.” 
(Cambridge Natural History. ) 
All of our native ants, with the possible exception of the house 
ant just mentioned, live in galleries and chambers in the ground. It is 
said that some species dig as deep as nine feet. The underground 
excavations are generally accompanied by hills of various sizes on the 
surface. 
Conditions under which ants are troublesome are so varied that 
individual cases should be referred to Experiment Station authorities. 
The family is well represented in Minnesota Camponotus, Lasius, 
Formica, Myrmica and A phaenogaster. 
CHRYSIDOIDEA 
Abdominal segments not strongly differentiated as petiole and gaster; tegulae 
present, wings usually well developed, sometimes vestigial or lost; hairs of dorsulum 
simple, not branched or plumose; abdomen with three segments visible, segments be- 
yond third hidden. 
These are the most brilliantly colored of the wasps. Some may be 
iniquilines or “guests,” though Ashmead believed they are all para- 
