The Biology of Maine Species of Altica. 173 



Natural Enemies.- 



Fungous diseases. Both in the laboratory and in the field, 

 larvae, pupae, and adults are all very susceptible to the attacks 

 of the parasitic fungus, Sporotrichum globuliferum Speng. This 

 widely distributed fungus destroys many of these insects when- 

 ever conditions are favorable for its growth, and is without doubt 

 an important agent in holding this species in check. 



The prepupae and pupae are quite subject to a wilt disease, 

 which is probably bacterial in its nature, although the writer has 

 not made any attempt to isolate the causative organism. 



Insect parasites. The writer has bred only a single parasite 

 from the dogwood flea-beetle, a tachinid fly which works in the 

 adult beetles. This fly which is not very common in Maine was 

 determined for the writer as Celatoria spinosa Coquillet by Mr. 

 C. W. Johnson of the Boston Museum of Natural History. The 

 writer has also bred this fly from the beetles of Altica ulmi (see 

 page 193), and it has been recorded by Coquillet as bred from 

 the adults of Diabrotica soror LeC (Coquillet 1890, Insect Life, 



V.2I235). 



The larvae are internal parasites of the adult beetles. The 

 writer has but little data on the life history, but it seems prob- 

 able that the flies deposit eggs on the over-wintering beetles in 

 the spring or summer after they have come out from hibernation. 

 The whitish larvae emerge from the beetles when they are full 

 grown, killing their host. In a few hours they shrink up into 

 brown puparia, and the adult flies emerge a week or ten days la- 

 ter. 



Control. 



Like most flea-beetles, these insects can be controlled by ar- 

 senical sprays. A thorough spraying with arsenate of lead at 

 the ordinary strength (3 pounds of the paste or 1 y 2 pounds of 

 the powder to 50 gallons of water) as soon as the beetles appear 

 in the spring, and repeated in late June and mid-July for the 

 larvae, is necessary, will hold this species in check whenever it 

 is practicable or desirable to try to keep down their numbers. 



