Insect Notes for 1920 7 



forgotteiv. and a strong force of helpers during the growing season 

 must be kept on the alert. We believe the work should be continued 

 until it is demonstrated beyond doubt that barberry eradication pays. 



Insect problems of the year. — The usual pests of the year have 

 been present, some of them more and some less abundant than usual. 

 Some new insects, as the apple maggot, Rhagolcfis pomoncUa Walsh, 

 and the asparagus beetle, Cr'wccris asparagi Linn., have made their 

 appearance in the state. These have already caused considerable dam- 

 age. Other insects found for the first time this year, as some of the 

 bugs and aphids, will probably be heard from later. The new pests are 

 being studied carefully, as well as the whole group representing the 

 bugs and aphids, so that it is hoped any outbreak can be reported on 

 immediately with methods of control. 



Apple maggot. — In 1914 when asked by Professor W. C. O'Kane, 

 of New Hampshire, whether the apple maggot was a pest of Minne- 

 sota the reply was, that so far Minnesota had experienced no trouble 

 from the insect. Specimens of the fly Rhagolcfis pomonclla Walsh, 

 were in our collection, found in 1898 on Crataegus, but no reports were 

 on record that the insect had damaged cultivated fruit. The first re- 

 port of injury came in 1918. In 1919 the reports were more numerous 

 and in 1920 the injury done by this insect was very severe. All of the 

 best apple growing areas were afifected, which means practically the 

 southern half of the state. 



The common hosts of the insect in Minnesota are the common 

 varieties of apples like the Strawberry crab. Wealthy, Malinda, Peer- 

 less, Northwestern Greening, and Patten's (jreening. Beside the host 

 plants of apples and Crataegus, Dr. H. H. Knight added this year 

 the wolfberry Syiiipliiocarpos occidciitalis Hook. He found the white 

 berries in August and September greatly infested. 



Damage is done by the insect in both the larval or immature stage, 

 and in the adult. The adults are flies, slightly smaller than houseflies 

 and may be distinguished by the peculiar black bands across the wings. 

 They are found flying during the months of July, August and Sep- 

 tember, most of the eggs probably being laid in July or August. Be- 

 fore egg laying begins the flies may be seen alighting on the surface of 

 the fruits and leaves, rasping the surface with their probosces, eventu- • 

 ally swallowing the removed particles. This process does not injure 

 the fruit materially but soon after feeding, egg laying begins. The 

 eggs are thrust through the skin by means of the ovipositor and where 

 each puncture was made there, later, often appears a depression or 

 dimple. The eggs hatch into maggots which eat through the pulp of 



