370 ECONOMIC ENTOMOLOGY 



long. Julus virgatus injures lettuce and /. coeruleocindus the fruit 

 and roots of strawberries. The young millipeds have only three pairs 

 of legs. Spirobolus is from 3 to 5 inches long. Polydesmus canadensis 

 is a deep brown flattened form. 



Oxidus gracilis is a common pest of greenhouses, sometimes occurr- 

 ing in millions in an abundant supply of decaying vegetable matter. 

 It attacks sprouting seeds, and burrows into the decaying spots of roots. 

 In color it is chestnut-brown marked in parts with lemon yellow. Gos- 

 sard says that the whitish eggs are laid in April and May in the soil 

 in masses of from 100 to 300 or more and hatch in about 20 days. So 

 far as known there is but one generation a year. 



Control. — (i) Trap with shces of beet or potato; (2) mix thoroughly 

 with the soil tobacco dust, gas lime (3 tons to acre in fall), or soot; (3) 

 give the soil a thorough drenching with kerosene emulsion or two or 

 three light dressings of nitrate of soda (100 lb. to acre). 



BRANCH MOLLUSCA 



Class Gastropoda 



Garden Slugs (Limax spp.). — Garden slugs are mollusks and not 

 arthropods, but may be treated here. They are frequently injurious 

 in moist situations to garden and greenhouse produce. They dislike 

 sand, sawdust and ashes as these dry up the secretion of mucus. They 

 spend the winter in the ground encased in their own slime. Some 

 species, however, winter in greenhouses and remain active through- 

 out the year. They are active at night, and feed upon green succulent 

 leaves, mushrooms and ripe fruit. 



There are three common injurious species: L. maximus, L. agrestis 

 and L. flavus. Slugs differ from snails in the apparent absence of a 

 shell, but in reality the shell is reduced to a thin horny plate embedded 

 in the mantle. 



The eggs are large, round, transparent, yellowish, occurring 

 in gelatinous clusters under boards or refuse. They hatch in spring 

 and the slugs become half grown by fall. The adults may live several 

 years. Blackbirds, toads, moles, centipeds, and poultry destroy 

 slugs and snails. 



Control. — (a) Trapping by placing out shingles or boards is quite 

 effective. Examine the traps every morning and crush the slugs col- 



