Maskell. — On Aleurodidas. 421 



had to do \Yith a Psyllid, and not with an Aleurodid, a fact of 

 which I had originally some suspicion when I saw the insects 

 on the upper instead of the under surface of the leaf. But 

 the very great dorsal similarity, at first sight, to an Aleurodid 

 showed the necessity of much care before arriving at a 

 decision. 



A paper on AleurodidcB would be incomplete without some 

 notice of the means available for destroying these injurious 

 insects, or at least minimising then- effects. They are very 

 closely allied to the Coccidce, and derive their nourishment from 

 plants in the same way — through their rostral tubes ; and a 

 similar mode of combatting them will be available for both 

 families. The most successful plan will therefore be, as for 

 CoccidcB, applications of kerosene emulsion in the form of 

 spray. I see no reason why the formula used against Coccids 

 should not be e;ood asrainst Aleurodids. That formula is as 

 follows : Take of common soap, |^lb. ; kerosene, 2 gallons ; 

 soft water, 1 gallon. First dissolve the soap in the water, 

 heated to boiling, then add the kerosene, and churn the 

 mixture until a creamy fluid results, which thickens on cool- 

 ing. Dilute with nine or ten (or, for tender plants, twelve to 

 fourteen) times the quantity of water. Apply in the form of 

 the finest possible spray by using one of the different kinds of 

 "cyclone " nozzle, in dry, and preferably cloudy, weather, re- 

 peating the dose after about ten days. 



The foregoing formula was recommended by me several 

 years ago in my " Scale-Insects of New Zealand," and I have 

 not seen any reason since to change it. 



The process just mentioned is intended for the larval and 

 pupal states of AleurodidcB, and will undoubtedly require some 

 care on account of the habit (already noted) of these insects 

 to attach themselves almost, if not quite, exclusively to the 

 under-sides of leaves, where it is, of course, difficult to get at 

 them. In the case of such trees as orange, or tall plants like 

 sugar-cane, the trouble is less than with low-growing plants 

 such as tomato, cabbage, or tobacco. Still, the spray may be 

 made to reach even these satisfactorily. 



When the Aleurodids are in their adult stage they may be 

 treated like Aphides on roses or other plants, and tobacco- 

 water, or soapsuds, or the well-known " Gishurst compound " 

 may be used. If not over too large an area, advantage may be 

 taken of their habit of rising on the wing in numbers when 

 the plant is disturbed, and then after a few minutes settling 

 again. While in the air they may be easily caught, some- 

 times in hundreds, in an ordinary entomological net, and 

 destroyed. 



