66 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
man (152). Severe infestations may build up after spraying with 
Db 
Tetranychus telarius Li. is a species of nearly world-wide distribu- 
tion, attacking many species of hardwoods and evergreens. It is our 
most common and injurious species. 
The European red mite (Paratetranychus pilosus C. & F-.), 
European species now established in this country, is injurious to shade 
trees, particularly basswood or linden, maple, elm, and willow, often 
causing the leaves to fall. 
Oligonychus americanus Ewing has been abundant on pine seedlings 
in the nurseries of the Middle West. 
Control of the red spiders is discussed on pages 37-88. 
THE HARVEST MITES AND CHIGGERS 
FAmMity TROMBIDIIDAE 
The harvest mites resemble the red spiders, but are much larger, 
particularly a bright red species commonly found moving slowly about 
on the moist leaf litter or on logs in woodlands. 
Red bugs or chiggers need no description, because the annoying 
itching sores produced by these minute animals after they attach 
themselves to the skin are well known to all foresters in the Central 
and Southern States, along the seaboard into New Jersey, and occa- 
sionally in Pennsylvania. “Heavy attack on man may cause fever, and 
secondary infections can be very serious. Red bugs are the first instars 
of a rather large mite. Normally they feed on such animals as snakes, 
lizards, birds, and rodents. Certain local areas, such as briar patches 
and sunny exposures, are more heavily infested than other sites and 
can, with experience, be avoided to some extent. 
Prevention of attack by chiggers is better than cure. Clothing that 
will prevent access of the larvae to the skin is recommended. High 
boots and closely woven cotton trousers are excellent protection, and 
flowers of sulfur dusted into the clothing is effective. ‘The mosquito 
repellents mentioned on page 527 are effective in repelling chiggers. 
Derris powder is also effective and less irritating than sulfur. A 
thorough hot bath with a soapy lather immediately ¢ after returning to 
‘amp is simple and effective. The clothes that were removed should 
not be worn again until the following morning. Ammonia water, 
soda, cooling ointments, or colloidin help to allay itching. 
MARINE BORERS 
By R. A. St. GEORGE 
Serious damage to the submerged portions of marine piling, 
wharves, or other wooden members, fixed or floating in salt (and 
occasionally brackish) waters, 1s caused by certain molluses and 
crustaceans. 
Extensive damage occurs on the Atlantic, Gulf, and Pacific coasts, 
chiefly in warm souther n waters, but also to some extent in New Eng- 
land, Nova Scotia, and even in Newfoundland, where the waters are 
cold during much of the yea Under certain conditions these ani- 
mals are capable of conipletsie destroying untreated timbers in less 
