540 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
Hymenoptera. A few are phytophagous, but those species are rarely 
if ever injurious to woody plants. Other species are predators living 
in or among colonies of aphids or plant lice. Metcalf (295) listed the 
following genera having species that live in ca wood of trees: 
Mallota, Xylota, Brach ypalpus, Pocata, and Myiolepta; and those 
living in sap flowing from injured or diseased trees: Brachyopa, 
Chrysochlamys, Xylota, Ceria, and Myiolepta. Metcalf also listed 
species of the genus Xanthogramma that were bred from larvae found 
under the bark of oak and cottonwood trees. 
Additional rearing records in 1916 of species that have been found 
under bark, in tree pockets, etc., by Banks, et al. (20) are as follows: 
Brachyopa vacua O. S., Tubif era transversus Wied., Blera umbratilis 
(Will.), Alallota cimbiciformis Fall., I. posticata ¥., Xylota pigra 
i. Brachypalpus frontosus Loew, B. riley Will., Somula decora 
(Macq.), and Ceria abbreviata Loew. A species belonging to the 
Xylotinae has been recovered by Snyder from a prionid burrow in a 
chestnut pole. Z’emnostoma bombylans F. has been bred from hickory 
and willow logs and 7’. excentricum (Harr.) from elm logs. Accord- 
ing to Metcalf (297), the mature larva of Temnostoma balyras 
(Wikr. ) is about 14 inch long and white, except for the protho- 
racic rakes, which are composed of three rows of prominent teeth and 
black posterior spiracles. The mouth parts are inconspicuous, and 
the anterior and posterior segments truncate, with slightly raised 
spiracles. The larva of 7’. obscura Loew is very similar to that of 
T. balyras. 
Famiry MYCETOPHILIDAE 
Fungus Gnats 
The Mycetophilidae comprise a large number of terrestrial and 
semiaquatic species resembling mosquitoes, but differing in that the 
antennae are not verticillate. Ocelli usually are present and all the 
tibiae are spurred. The larvae have a complete head with opposed 
mandibles and abdominal spiracles. Three subfamilies are ncted. 
Species of the Sciarinae are frequently found in the galleries of wood- 
boring beetles or under bark. Leta bivittata Say has been reared 
from elm logs. The larvae of the Bolitophilinae feed on fungi grow- 
ing on trees and logs; those of the Platyurinae live in slimy webs 
on “fungi found on decaying timber. 
Famiry CHIRONOMIDAE 
The adults of the family Chironomidae resemble mosquitoes, being 
distinguished from the latter by the absence of scalelike hairs on the 
wing and by the discontinuation of the costal vein at the termination 
of the third vein. The larvae have a complete head and opposed man- 
dibles. They are usually cylindrical in form, with one pair of pseudo- 
pods present on the prothorax and one pair on the anal segment. 
Certain species are soft-skinned, wormlike, and frequently blood red 
in color, which causes them to be called “blood worms. 
Most of the species are aquatic and the adults often appear in great 
numbers in areas adjacent to or occasionally a considerable distance 
away from their breeding place. Although these great swarms of 
midges are the frequent cause of inquiry, they are for the most part 
