Mosquito bug (Helopeltis)

The earliest sign is many small dark-brown to black sunken spots and streaks, like little scabs or dried water-blisters, often bunched together where the bug fed over and over. A fresh spot may weep a bead of gum or look water-soaked, then dries down to a black, sunken scar.

On the flower sprays (the panicles — the branched heads of tiny flowers) the flowers blacken and dry up — this is called 'blight' — and set no nuts or fruit. On young nuts and fruit you see rough, scabby, cracked, corky patches, and many of the small ones drop off. Badly hit shoot tips curl, wilt and die back from the tip downward.

is slender and long-legged — about the size of a mosquito, roughly 6–10 mm long — with thread-like feelers (antennae) longer than its own body. Its give-away is a tiny pin or nail standing straight up on the middle of its back; no other bug on your crop carries this. Colour varies: on cashew it is often a reddish-orange front body, a dark head and black-and-white banded legs; on tea it looks more greenish-brown.

are just a smaller copy of the adult: pale yellow to reddish, slightly fuzzy, and they run fast, almost like tiny ants. The mosquito bug is shy — it hides on the shaded underside of shoots and is easiest to spot in the cool of early morning or late afternoon. In the hot middle of the day it hides, and when you disturb it, it darts to the far side of the shoot, drops, or flies off.

It is not a true mosquito — it does not bite people, it is bigger, and it carries that pin on its back. Its spotting can look like anthracnose dieback (a fungus disease), but the fungus spreads as soft blotches in wet weather and leaves no insect behind — with the mosquito bug you find separate puncture-spots plus the slender bug itself on the tender growth. Silvery, scratchy leaf-bronzing with no sunken black spots is thrips or mites, not this pest.

when it pushes out new flush (the soft reddish new leaves and shoot tips) and when it is flowering and setting young nuts or fruit. These are the two windows when the bug feeds and breeds, so go through them at least twice a week — not just now and then.

, when the bugs are active and out in the open. In the hot middle of the day they hide on the shaded underside and you will walk straight past them.

so you cover all four corners and the middle — not only the trees along the path. Stop at about 10 trees spread along the way.

and every flower spray and young nut or fruit cluster you can reach, turning them over to check the shaded underside. Hunt for the fresh dark sunken spots and for the slender long-legged bug with the pin on its back.

You do not wait for many. Put simply: if you find fresh feeding or a live bug on about 1 in 10 trees during flushing or flowering, start control now. This pest builds fast and does its worst quietly, so early is everything.

The mosquito bug loves warm, damp, shady, crowded canopies (still, humid air is where it thrives). Prune your trees so light and air pass right through, cut out crowded and dead wood, and clear weeds and bushy plants around them. A drier, airier canopy is far less welcoming to the bug.

Pull out nearby other host plants it also lives on (other bushy hosts and volunteer seedlings), and where you can, help the tree flush all at once instead of dribbling out soft new growth non-stop — a short, even flush gives the bug less tender food to jump between. The moment you see them, cut off and burn or bury the worst blackened shoots and blighted flower sprays — this takes out bugs and damage in one move.

In cashew, the reddish weaver ants (Oecophylla) that stitch leaves into nests up in the tree are a proven control: they patrol the shoots all day long and drive off and eat the bugs. Do not destroy their leaf-nests, and tie strings or lean branches between trees so the ants can spread from tree to tree. Spiders and other small predators help too — so avoid broad, everything-killing poisons that wipe them out.

If your scouting hits the threshold during flushing or flowering and the natural helpers cannot hold it, use a registered insecticide (one approved for your crop and this pest), aimed to cover the tender flush, flower sprays and young fruit where the bugs actually feed. Spray in the cool, still hours of early morning or evening. It is the strongest tool, but it also kills weaver ants and other helpers, so use it sparingly and only when the count says you must.

Cover your skin, eyes, nose and mouth; spray with the wind at your back so the mist blows away from you; keep it off food, off drinking water, and away from children, animals and bees; and wash yourself and your clothes well afterwards. Always wait the pre-harvest interval — the number of days the label tells you to leave between the last spray and picking — so the nuts, fruit or tea leaf are safe to eat and sell.

If you must spray again, rotate to a different chemical group each time (ask your agro-dealer which group a product belongs to). Using the same one over and over lets the bug become resistant — used to the poison — until it no longer kills.

go back over the plot, cut out and burn or bury every blackened, dying shoot and blighted flower spray, tighten your pruning and weeding to dry out the canopy, and switch to a different insecticide group for the next round. When a flush or a flowering is already lost, stop spraying a ruined crop — that yield is gone. Instead keep the tree itself strong with water and feeding, and put your effort into protecting the next flush, which on these tree crops is your real chance to recover.