HANDBOOK ON INSECT ENEMIES OF FLOWERS AND SHRUBS 61 



infested bulbs after digging them, to 

 prevent the larvae from completing 

 their development. A convenient 

 method for the average gardener is to 

 treat the stock for \){ hours in hot 

 water held at a temperature of 110°- 

 111.5° F., following the procedure given 

 for treating tulip bulbs infested with 

 root aphids (p. 87). Dry the bulbs 

 thoroughly before returning them to 

 storage. Another method is to fumi- 

 gate the bulbs with calcium cyanide, 

 using the granular form, at the rate of 

 16 ounces to each 100 cubic feet of space 

 with a 4-hour exposure in a tight 

 fumigation chamber. The bulbs and 

 chamber temperature should be held 

 at about 75° F. during the exposure. 



Caution. — Since calcium cyanide and 

 the gas it produces are deadly poison, 

 it should be used only by those familiar 

 with the hazards involved. 



Prevention. — There is little than can 

 be done to eliminate an infestation 

 after it has gained a foothold in the 

 growing plants, except to dig up and 

 destroy all weak and sickly looking 

 plants and to dig up all blank spaces, as 

 one is quite certain to find infested bulbs 

 in such spots. Examine the bulbs 

 carefully at planting time and destroy 

 all that are definitely recognized as 

 being infested. 



Lesser Bulb Flies 



Three species are often referred to as 

 lesser bulb flies, but only one is of 

 major importance, namely, Eumerus 

 tuberculatus Rond. The maggots, on 

 hatching, work their way into the 

 interior of the bulb (fig. 99) and usually 

 cause it to rot completely. Although 

 the maggots can injure healthy bulbs, 

 their presence is more often associated 

 with weak, sickly, or decaying bulbs, 

 or stocks that have been previously 

 injured from other causes. Practically 

 all flowering bulbs are attacked, as 

 well as certain vegetable crops, includ- 

 ing cabbage, carrot, garlic, onion, 

 parsnip, potato, and shallot. Unlike 

 the narcissus bulb fly, the maggots 

 of this species occur in large numbers 

 within a bulb. The maggots are about 

 Yz to x /% inch long, dirty grayish yellow, 

 and wrinkled. They pupate in the 

 bulbs or in the ground close to the 

 bulbs. Two or more generations de- 

 velop annually. The flies (fig. 98, A), 

 which are about the size of a housefly, 

 usually appear late in April or early in 

 May and some are present throughout 

 the summer. They are often found 

 frequenting flowers, especially on bright 

 sunny days. The eggs are laid near the 

 base of the plant. 



749493°— 48 5 



Figure 99. — Narcissus bulb showing 

 maggots and injury of the lesser bulb 

 fly, Eumerus tuberculatus. Slightly 

 reduced. 



Treatment and prevention. — Same 

 as for the narcissus bulb fly, discussed 

 above. 



Bulb Mite 



Several species of mites may attack 

 the roots, bulbs, and corms of various 

 flowering plants. The more important 

 of these are the bulb mite (Rhizoglyphus 

 echinopus Fum. and Rob.) and the bulb 

 scale mite, discussed in the next section. 



The bulb mite has many food plants, 

 but narcissus, lily, crocus, amaryllis, 

 dahlia, gladiolus, hyacinth, tuberose, 

 and tulip are among the bulbous plants 

 most frequently attacked. Mite-in- 

 fested narcissus bulbs become soft and 

 give easily when squeezed. The stem 

 of an infested lily breaks over readily, 

 and in a tuberose bulb (fig. 100) the 

 embryo flower is destroyed. Mites are 

 more of a problem in storage, where, 

 under favorable conditions, an enormous 

 population develops rapidly. Infested 

 stocks, when planted, usually produce 

 weak and sickly plants or no growth at 

 all. This mite is usually considered a 

 scavenger, feeding on weakened plants 

 or plant parts, although it has been 

 observed working in normal tissue. 

 The mites (fig. 101) are very tiny, 

 plump, oval, opaque, white-bodied crea- 

 tures with reddish-brown legs and 

 mouth parts. They move rather slug- 

 gishly. 



